An explosion at a fertilizer plant Wednesday night in the town of West killed an estimated five to 15 people, injured more than 150 and damaged dozens of homes and buildings, officials said.

Overnight, hundreds of emergency responders descended on West — a town of about 2,800 located 20 miles north of Waco — where scores of people were sent to area hospitals and dozens of homes, apartments and a nursing home were toppled or damaged, officials said.

“There is massive devastation” throughout the community, Waco police Sgt. W. Patrick Swanton said earlier in a news conference.

Gov. Rick Perry declared a state of emergency in McLennan County, sending state emergency responders to help, and asked for a federal emergency declaration to help bring assistance to the victims.

Perry said President Barack Obama, in a phone conversation Thursday morning, promised a quick turnaround on the state’s request.

Officials have not determined an exact cause of the blast, which registered as a 2.1 magnitude earthquake, the U.S. Geological Survey said.

Another press conference is scheduled for 4 p.m., officials said.

McLennan County Chief Deputy Matt Cawthon said that by the time he arrived, the smell of ammonium nitrate was overwhelming. The destruction wrought by the explosion was “absolutely” like a war-zone, he said.

“You can’t imagine the devastation outside of a missile attack or something like that,” he said. “It was sad — surreal at times. People were hurt. People were confused.”

Crews continued to search for people in West on Thursday morning, but at 10:45 a.m. Swanton did not have a firm number of how many people are missing or dead.

At least four volunteer firefighters are thought to be among the fatalities, but that has not been confirmed, said Chris Barron, executive director of State Firemen’s and Fire Marshals’ Association.

West has an all-volunteer fire department with 29 members, five of whom have advanced firefighter certification, he said. “It’s a very respected department,” Barron said.

Crews arrived to the scene of a fire at West Fertilizer about 7:30 p.m. Wednesday and were fighting it when the explosion was reported at 7:53 p.m., Swanton said.

Swanton said 50 to 75 homes, numerous businesses, an apartment complex and multiple cars were damaged. He did not have exact details but said it’s possible homes as far away as five blocks were damaged.

“Some homes have been leveled, some have windows blown out,” he said.

He said crews have had to reinforce some homes and buildings before entering them.

“It is tedious. It is time consuming,” Swanton said.

The No. 1 priority is to save lives, the second priority is to make sure nobody else gets hurt, Swanton said.

Nearby hospitals reported treating more than 150 patients. Officials said many people suffered minor to serious injuries ranging from cuts and bruises to broken bones.

As of 3 p.m., Scott & White hospitals in Temple said they have been treating five people injured in the West explosion. Three patients are at Scott & White Hospital in Temple, with two patients in critical condition and one in fair condition, according to an update posted on the system’s website. McLane Children’s Scott & White Hospital is treating two patients, one in critical condition and one in serious condition.

April Foran, a spokeswoman for Parkland Memorial Hospital in Dallas, said the hospital has received two patients from West.

Both are in serious condition, she said.

Katherine Voss, a spokeswoman for Scott & White Healthcare, said four patients from West were in Central Texas hospitals, including two in critical condition.

St. David’s Medical Center in Austin isn’t expecting any patients from West, a spokeswoman said in a statement, but the hospital is coordinating with local, regional and statewide agencies responding to the explosion.

Hundreds of emergency responders from Killeen to Dallas have descended on the town.

Seven Austin firefighters were deployed to West, department spokeswoman Michelle Tanzola said. The group is part of Texas Task Force 1, the state’s elite wide-area search team that has worked national disasters such as Hurricane Katrina in New Orleans in 2005 and the World Trade Center terrorist attacks in New York 10 years ago.

They’re expected to be there for at least a few days, Tanzola said.

Austin police officials said no officers have been sent to assist in West.

The Central Texas unit for the American Red Cross said it mobilized local volunteers in Austin and Waco. The agency said it was working with West emergency management workers to identify shelters and help manage assistance to victims.

The federal Bureau of Alcohol, Tobacco and Firearms is leading the investigation, Swanton said.

The U.S. Chemical Safety Board has also deployed a large investigation team to the scene of the explosion to search for physical causes as well as any possible inadequacies in regulations, industry standards and safety management systems.

An independent federal agency charged with investigating industrial chemical accidents, the safety board does not issue fines or citations but does make recommendations to plants, regulatory agencies, industry organizations and labor groups.

The investigators will conduct detailed interviews with witnesses and plant employees, examine company safety records and operating procedures and test chemical samples. It typically takes several months before root cause findings and recommendations are released.

Through tears Thursday morning, Elizabeth Perez Marquez, described the horror of the night – how a quiet evening watching television with her two daughters quickly turned into mass destruction.

They live about a mile from the epicenter of the explosion and were watching television when their house began to shake dramatically — lifting a bed and other furniture off the floor — and nearly every window in the house shattered.

During the next few hours, Marquez said, she tended to patients from the West Rest Haven nursing home, comforting the injured, writing their names on patients who did not have an ID and even bandaging a few of their wounds.

“We were just helping as much as we could,” said Marquez, who suffered a leg injury.

Chief Nim Kidd, who heads the Texas Division of Emergency Management, said he would not second-guess the wisdom of applying water to the fire at the plant.

“A lot of people don’t like putting water and ammonium nitrate together and I believe that was one of the chemicals that was there,” Kidd said at a press conference at the Department of Public Safety headquarters in North Austin. “Usually when you mix those two you have to have something that confines it in order to to make it a dangerous product.”

But, he said, “I’ll tell you, a lot of firefighters will use their number one tool, which is water, in a hazardous materials, chemical situation like that to cool the surrounding environments, to cool those other things to keep them from cooking off or exploding. So again, too soon to really speculate was it the right place at the right time. I don’t think we should be second-guessing right now the actions of he fist-responders and whether they were applying water at the appropriate place at the appropriate time.”

12:50 update: Veronica Beyer, a spokeswoman with the Texas Department of Transportation, said that though traffic could be slow near West as drivers slow down to see what's happening, there are no known closures on Interstate 35.

12:37 p.m. update: Gov. Rick Perry said Thursday he has declared a state of emergency in McLennan County and said President Barack Obama, in a phone conversation this morning, promised a quick turnaround on the state's request.

“President Obama called from Air Force One as he was en route to Boston; we greatly appreciate his call and his gracious offer of support, of course, and a very quick turnaround of the emergency declaration that will be forthcoming and he offered his prayers,” the governor said in a press conference with public safety officials.

Perry said the state had brought all its resources to bear in dealing with the emergency.

“West is a really small community, just a few thousand people,” Perry said. “In a small town like this they know that this tragedy has touched practically everyone in that town, and I ask all Texans and all Americans to join me and Anita keeping them in their prayers.”

11:45 update: At least four volunteer firefighters are thought to be among the fatalities, but that has not been confirmed, said Chris Barron, executive director of State Firemen's and Fire Marshals' Association.

West has an all-volunteer fire department with 29 members, five of whom have advanced firefighter certification, he said. “It’s a very respected department,” Barron said.

Barron said that normally when fire breaks out at an industrial facility with high explosive potential, firefighters rely on the plant manager to give direction as to whether firefighters should attempt to extinguish the flames or pull back and let it burn. He did not know what the situation was in West last night.

“This was a humongous fire,” said Barron. “I don’t know if any fire department would have been able to put it out.”

11:40 update: The risk of rain and lightning strikes in West has passed, with the closest strikes now about 30 miles away from the town, said Steve Fano, a meteorologist with the National Weather Service.

“They should remain at least that far if not farther away,” he said at about 11:30 a.m.

Storms that developed over Killeen and Temple earlier Thursday morning were on track to move toward West but only one lightning strike touched ground about 10 miles east of the town, Fano said.

All the storms have dissipated or moved on, and no more rainfall is expected today, he said.

11:32 update: The Texas Department of Transportation has advised drivers to expect traffic delays because of the explosion in West.

11:17 update: Through tears Thursday morning, Elizabeth Perez Marquez, described the horror of the night – how a quiet evening watching television with her two daughters quickly turned into mass destruction.

They live about a mile from the epicenter of the explosion and were watching television when their house began to shake dramatically — lifting a bed and other furniture off the floor — and nearly every window in the house shattered.

During the next few hours, Marquez said, she tended to patients from the West Rest Haven nursing home, comforting the injured, writing their names on patients who did not have an ID and even bandaging a few of their wounds.

“We were just helping as much as we could,” said Marquez, who suffered a leg injury.

Texas A&M University’s veterinary emergency team went to West on Thursday morning in response to a request from the Texas Division of Emergency Management and an urban search-and-rescue team, according to a statement posted on the emergency vet team’s Facebook page.

The team provides care to animals in disaster-stricken areas.

“As we head down the road, we know that we will be very busy as soon as we hit the ground in West,” the statement said.

Representatives for the team could not immediately be reached for comment.

10:45 a.m. update: Crews continue to search for people in West, but Swanton did not have a firm number of how many people are missing or dead.

He said crews have had to reinforce some homes and buildings before entering them.

“It is tedious. It is time consuming,” Swanton said.

The No. 1 priority is to save lives, the second priority is to make sure nobody else gets hurt, Swanton said.

Swanton did not have an updated number on the number of people injured.

He said three to five firefighters are still missing, “but again, that information is sketchy and limited to me.”

10:40 a.m. update: Hillcrest Baptist Medical Center in Waco said it has treated multiple patients from the West blast.

The hospital said of 28 people admitted and who continue to receive care, five are in the intensive care units and two children were transferred to McLane’s Children’s Scott & White Hospital in Temple.

"Additionally, 12 elderly patients, who were reportedly nursing home residents from West, were able to be treated and discharged to alternative nursing home facilities," the hospital said in a statement. "In addition to the patients who were admitted, transferred or discharged to another healthcare facility, more than 50 patients were treated and released from the Emergency Department and left with family and friends."

10:21 update: The U.S. Chemical Safety Board has deployed a large investigation team to the scene of the explosion to search for physical causes as well as any possible inadequacies in regulations, industry standards and safety management systems.

An independent federal agency charged with investigating industrial chemical accidents, the safety board does not issue fines or citations but does make recommendations to plants, regulatory agencies, industry organizations and labor groups.

The investigators will conduct detailed interviews with witnesses and plant employees, examine company safety records and operating procedures and test chemical samples. It typically takes several months before root cause findings and recommendations are released.

9:58 update: Scattered thunderstorms were developing over Temple and Killeen at about 9:45 a.m. and, if they hold together, are expected to arrive in West in about an hour, said Dennis Cavanaugh, a meteorologist with the National Weather Service.

The storms should produce only brief to moderate rainfall, Cavanaugh said, and strong winds and hail are not expected.

The main concern is cloud-to-ground lightning strikes, particularly with the number of people outside in West, he said.

Temperatures mid-morning were in the upper 40s, he said, and are expected to climb to the low 50s this afternoon.

Cavanaugh said the weather service has provided updates to authorities in West, but that he doesn’t know what the weather’s immediate impact will be on responders.

Update 9:50 a.m.: At a press conference, Swanton said crews are still searching for missing people, including three to five firefighters.

Swanton did not have an exact number of how many people have been rescued or how many people were killed in the blast.

He estimated the death toll to be five to 15, though he called that “a rough number.”

Swanton had no information on the cause of the blast. The fire is still burning but has been contained, he said.

The missing firefighters were part of a volunteer force that first responded to the blaze before the explosion.

Swanton said 50 to 75 homes, numerous businesses, an apartment complex and multiple cars were damaged. He did not have exact details but said it’s possible homes as far away as five blocks were damaged.

“Some homes have been leveled, some have windows blown out,” he said.

April Foran, a spokeswoman for Parkland Memorial Hospital in Dallas, said the hospital has received two patients from West with blast-related injuries.

Both are in serious condition, she said.

Katherine Voss, a spokeswoman for Scott & White Healthcare, said four patients from West were in Central Texas hospitals, including two in critical condition.

St. David’s Medical Center in Austin isn’t expecting any patients from West, a spokeswoman said in a statement, but the hospital is coordinating with local, regional and statewide agencies responding to the explosion.

Seven Austin firefighters were deployed to West on Thursday morning to help with the aftermath of the explosion, department spokeswoman Michelle Tanzola said. The group is part of Texas Task Force 1, the state’s elite wide-area search team that has worked national disasters such as Hurricane Katrina in New Orleans in 2005 and the World Trade Center terrorist attacks in New York 10 years ago.

They’re expected to be there for at least a few days, Tanzola said.

The White House issued a statement, which read in part: “Today our prayers go out to the people of West, Texas in the aftermath of last night’s deadly explosion at a fertilizer plant. A tight-knit community has been shaken, and good, hard-working people have lost their lives. … My Administration, through FEMA and other agencies, is in close contact with our state and local partners on the ground to make sure there are no unmet needs as search and rescue and response operations continue.”

Update 8:15 a.m.: A spokeswoman with the Parkland Health & Hospital System in Dallas said that they're treating patients from the blast, but the exact number of patients was unknown at about 8:15 a.m. Thursday.

An official at Brooke Army Medical Center in San Antonio said it had not received any patients from West.

A division of the American Red Cross has opened a shelter in the nearby town of Aquilla but most people displaced from their homes seem to be staying with friends or family, said Marty McKellips, chief executive officer for the nonprofit’s Central Texas Region.

About 50 volunteers from Austin and Fort Worth are already trying to help at the scene of the blast and others are coming in from other parts of the state, McKellips said.

McKellips said she expects to start distributing supplies Thursday or Friday to help people clean up if they’re returning to homes with damage, such as broken glass.

She said she also anticipates a multi-agency center will be established Thursday or Friday to coordinate response efforts so that those affected by the explosion can get the help they need in one place.

McKellips said that the Red Cross is ready to increase its response to the incident as necessary, and that she would know more about the scale of destruction as the sun comes up.

6:45 a.m. update: A cold front that is moving through the town is expected to shift winds of 25 to 35 mph with gusts of up to 40 mph to the northwest, said forecasters for the National Weather Service. The system could also bring rainfall of one-quarter inch to one-half inch, forecasters said.

Temps were also slated to drop about 20 degrees into 50s, forecasters said.

“That will bring some issues for personnel response” at the scene, said Dan Huckaby, meteorologist for the National Weather Service.

The federal Bureau of Alcohol, Tobacco and Firearms is leading the investigation into the blast, Swanton said.

Several emergency responders from firefighters to at least one law enforcement officer remained unaccounted for, he said. The emergency workers had been at the scene of the fertilization plant fighting an earlier fire before the explosion occurred shortly before 8 p.m., officials have said.

Swanton said initial crews arrived to the scene of a reported fire at 7:29 p.m. before the fire was reported at 7:53 p.m.

Austin-Travis County Emergency Medical Services said it had dispatched two commanders to Waco to act as liaison for two Texas task force teams on standby for the explosion. The Central Texas division of the American Red Cross said they mobilized local response to the scene to assist with shelters and other efforts.

The blast registered as a 2.1 magnitude earthquake, the U.S. Geological Survey said.

5:15 a.m. update: Officials now estimate 5 to 15 people may have been killed in an explosion late Wednesday at a fertilization plant outside Waco.

The update was the first glimpse into the extent of potential fatalities following the devastating blast in West — a town of about 2,800 located 20 miles north of Waco — that sent more than 150 injured to area hospitals and toppled or damaged dozens of homes, apartments and a nursing home residence.

“There is massive devastation” throughout the community, Waco Police Sgt. W. Patrick Swanton said in a news conference.

The federal Bureau of Alcohol, Tobacco and Firearms is now leading the law enforcement investigation into the blast, said Swanton.

Leading the concerns of fatalities triggered by the blast, Swanton said there are several emergency responders from firefighters to at least one law enforcement officer who remain unaccounted for. The emergency workers had been at the scene of the fertilization plant fighting an earlier fire before the explosion occurred shortly before 8 p.m., officials have said.

Swanton said initial crews arrived to the scene of a reported fire at 7:29 p.m. before the explosion was reported at 7:53 p.m.

Now, hundreds of emergency responders from Killeen to Dallas who have descended on the small Texas town are continuing search and rescue operations to find any new potential survivors, he said.

Austin-Travis County Emergency Medical Services said it had dispatched one commander to Waco to act as liaison for two Texas task force teams on standby for the explosion. The Central Texas division of the American Red Cross said they mobilized local response to the scene to assist with shelters and other efforts.

The blast registered as a 2.1 magnitude earthquake, the U.S. Geological Survey said.

An approaching storm system could trigger a new slate of challenges for emergency responders and victims with the potential for a shift and increase in winds, possible heavy rains and other severe weather threats.

Temps will drop about 20 degrees into 50s, said Steve Fona, Fort Worth-based meteorologist for the National Weather Service.

“Big changes in weather are expected,” Fona said. The shift “is expected in the next couple of hours.”

Winds, currently blowing north, will shift toward the Southeast with speeds of 20 to 25 mph and gusts of up to 35 mph, Fona said. They could see rainfall totals of one-half to one inch of rain, Fona said.

High winds heightened concerns Thursday of any toxic fumes potentially released from the blast and carried to nearby communities.

For Austin, “that shouldn’t be an issue,” said Bob Fogarty, a service meteorologist based in New Braunfels.

The West winds, he added, point to a region northeast of the Austin area.

4:30 a.m update: An approaching storm system could trigger a new slate of challenges for emergency responders and victims alike following a devastating explosion that left dozens injured and multiple fatalities at a fertilizer plant outside Waco early Thursday.

Forecasters said an approaching cold front could bring a shift and increase in winds, possible heavy rains and other severe weather threats to the scene of the explosion in West, a town of about 2,800 located 20 miles outside Waco.

And later today, temps will drop about 20 degrees into 50s, said Steve Fona, Fort Worth-based meteorologist for the National Weather Service.

“Big changes in weather are expected,” Fona said. The shift “is expected in the next couple of hours.”

The blast, which the U.S. Geological Survey registered as a 2.1 magnitude earthquake, left several dead, more than 150 injured and dozens of homes toppled or damaged, officials said. The blast occurred shortly before 8 p.m. after emergency crews responded to the scene for a report of an earlier fire at the West fertilization plant.

Several local firefighters and at least one police officer was accounted for following the blast, an official said.

Winds, currently blowing north, will shift toward the Southeast with speeds of 20 to 25 mph and gusts of up to 35 mph, Fona said. They could see rainfall totals of one-half to one inch of rain, Fona said.

High winds heightened concerns Thursday of any toxic fumes potentially released from the blast and carried to nearby communities.

For Austin, “that shouldn’t be an issue,” said Bob Fogarty, a service meteorologist based in New Braunfels.

The West winds, he added, point to a region northeast of the Austin area.

Officials said emergency workers were still in search in rescue mode early Thursday, searching the devastation for any new survivors.

Hundreds of emergency responders from Killeen to Dallas descended on the small Texas town as they directed residents to evacuate. The Central Texas division of the American Red Cross said they mobilized local response to the scene to assist with shelters and other efforts.

3 a.m. update: Emergency responders continued to search for survivors amid a scene of massive devastation left by an explosion at a fertilizer plant outside Waco early Thursday even as the threat of multiple casualties grows.

Officials would only say “there had been fatalities” following the Wednesday night explosion at the fertilization plant in West — a town of about 2,800 located 20 miles outside Waco — but said they would not speculate how many.

The blast, which was felt as far away as Waxahachie, registered as a 2.1 magnitude earthquake, according to the U.S. Geological Survey.

“We are seeing quite a bit of devastation,” Waco Police Sgt. W. Patrick Swanton said in a news conference. “We don’t know the numbers of (dead) yet, they are still pulling victims out. We don’t want to guess.”

Officials have confirmed several people are unaccounted for, including several local firefighters and at least one police officer, Swanton said. The emergency workers had responded to an earlier fire at the plant before the blast was reported shortly before 8 p.m. Wednesday.

Swanton said emergency crews were still assessing structural damage and the safety for responders to search devastated residences for more potential survivors. Utilities had been shut off to much of the town as crews searched, he said.

Nearby hospitals reported treated more than 150 patients following the blast, saying many suffered minor to serious injuries ranging from cuts and bruises to broken bones. More than a 100 residences, including apartments, houses and a nursing home, were toppled or damaged in the blast, officials have estimated.

Hundreds of emergency responders from Killeen to Dallas descended on the small Texas town as they directed residents to evacuate. The Central Texas division of the American Red Cross said they mobilized local response to the scene to assist with shelters and other efforts.

And a team of federal investigators deployed by the U.S. Chemical Safety Board was headed to Central Texas Thursday to investigate the blast, the Associated Press reported.

Also early Thursday, emergency responders braced for an approaching cold front threatening to bring a potential for rain, high winds and other severe weather later this morning. Temps were also slated to drop dramatically Thursday.

Officials said they continued to work with the National Weather Service to assess the prospect of shifting and high winds along with concerns of toxic fumes from the blast being carried to nearby communities.

Earlier: A massive explosion at a fertilizer plant triggered reports of mass injuries, destruction and evacuations at a Texas town outside Waco late Wednesday, drawing emergency responders from across the state.

Emergency responders from Killeen to Dallas descended on the small Texas town of West to treat an estimated 100 or more injured in the blast, converting a football field into a triage center and routing dozens of patients to nearby hospitals.

The blast, which happened shortly before 8 p.m. and was felt as far away as Waxahachie, registered as a 2.1 magnitude earthquake, according to the U.S. Geological Survey.

“Massive,” Texas Department of Public Safety spokesman D.L. Wilson told CNN describing the scene. “Just like Iraq.”

The number of fatalities was not known early Thursday, and officials cautioned against any assumptions as they treated the wounded, although they said the blast would likely turn up casualties. Officials were expected to detail specifics on any fatalities later Thursday morning.

Officials also estimated as many as 100 or more nearby residences, from homes to apartments to a nursing home, were toppled or damaged in the blast.

Soon after the blast, law enforcement began advising residents to evacuate West immediately, as fears surged of an additional explosion. The local school district said its campuses would be closed for the rest of the week.

West, with a population estimated at more than 2,600, is located about 20 miles north of Waco.

An estimated 700 emergency workers, from law enforcement to emergency medical service personnel from Killeen to Dallas, responded to the scene by early Thursday, media outlets reported.

Locally, Austin fire officials reported no local resources were requested as of early Thursday. Also, local hospitals did not report any patients from the scene.

The Central Texas unit for the American Red Cross, however, said it mobilized local volunteers in Austin and Waco to the incident. The agency said it was working with West emergency management workers to identify shelters and help manage assistance to victims.

The agency said it was not sure what their blood donation need will be for victims of the West explosion, although they said such donations are always needed. For now, they directed anyone with interest to help to the Carter Bloodcare center in Waco, which will begin accepting donations starting at 9 a.m. today.

An official for Hillcrest Baptist Medical Center in Waco said they had treated more than a 100 patients by early Thursday, and was hopeful since many of the injuries were minor. At Providence Healthcare Network, an estimated 60 patients had been treated, with reports of traumatic injuries such as broken bones, cuts and bruises from flying debris.

By 1 a.m., Scott & White Hospitals in Temple reported treating five patients, including two pediatric patients at McLane Children’s Hospital. Two of the five patients were listed in critical condition, an official said.

Scott & White advised concerned relatives to call (888) 394-4947.

The hospital system also said its blood donation center at its Temple location would stay open until 2:30 a.m., and reopen at 8 a.m. to allow area residents to come in to donate.

Emergency responders from Killeen to Dallas were working furiously through the night to attend to the wounded, and by early Thursday had commenced search and rescue efforts of damaged residences to ensure no other survivors remained.

Among those emergency workers who responded nearby, hazardous material personnel from the Temple Fire & Rescue and the Killeen Fire Department were sent to West to assist in detecting and cleaning up chemical leaks, while Fort Hood sent two fire engines and a command patrol car.

American-Statesman Staff Writer Julie Chang contributed to this report