DALLAS — Texas State Trooper B. Borja and Dallas Police Officer M. Harder are stationed for who knows how long at the perimeter of the huge crime scene in the middle of downtown. People whose cars are parked inside the crime scene tape are out of luck for the moment, businesses within the enclosed area are shuttered temporarily and traffic is being diverted.

Residents have been stopping by periodically to ask for updates but mostly to express their support.

“We appreciate it,” Borja said after a few people stopped by to shake hands Saturday morning. “Hopefully, we’ll never have to go through something like this again.”

The shooting deaths of four Dallas police officers and a Dallas Area Rapid Transit officer, killed by sniper fire after a Thursday night march to protest police brutality, have left the city rattled yet determined to unify.

Metro Atlanta native the Rev. Jeff Hood began Thursday evening leading the protest, which followed two shooting deaths of black men by police in other states, and ended it by praying for the officers who were killed or injured.

“For maybe a millisecond, I thought, ‘Maybe this is fireworks,’” said Hood, who grew up in Jonesboro and attended Emory University’s Candler School of Theology. “It became very apparent very quickly that it was shots. I had 800 people behind me. I was screaming, ‘Run, run, run!’”

He said he was devastated at the injuries and loss of life.

“I saw two officers on the ground right after they got shot. All I knew to do was pray, scream and get people out of there,” Hood said. “We were marching right into the gunfire. I was close enough to think that I might have gotten shot.”

Although there were hints that investigators may have been looking at multiple suspects early on, officials have since indicated that slain suspect Micah Xavier Johnson acted alone. Investigators discovered an arsenal of weapons and bomb-making materials at his suburban Dallas home.

Johnson served in the Army Reserve for six years, but was sent home from Afghanistan in May 2014, six months into his tour, and was recommended for separation “other than honorable discharge” after being accused of sexual harassment by a female soldier, The Associated Press reported.

“In his case, it was apparently so egregious, it was not just the act itself,” his military attorney, Bradford Glendening, told the AP.

President Barack Obama plans to visit Dallas in coming days, not quite a month since his June 16 visit to Orlando following the Pulse nightclub massacre that left 49 dead and many more wounded.

“The Dallas Police Department is a great example of a department that has taken the issue of police shootings seriously,” Obama said Saturday, speaking from the site of a NATO summit in Warsaw, Poland. He noted that the city has both curbed its murder rate and sharply cut complaints of police misconduct, saying, “That’s the spirit that I want to build on.”

Dallas Police Chief David Brown said that during negotiations, Johnson was clear in expressing his aims.

“He wanted to kill officers,” he said during a news conference. “The suspect stated that he wanted to kill white people, especially white officers. He expressed anger for Black Lives Matter.”

But the suspect acted alone and was not affiliated with any groups, Brown added.

“All I know is this must stop,” Brown said. “This divisiveness between our police and our citizens.”

He made an emotional appeal to the city’s residents in the hours after the attacks.

“We don’t feel much support most days,” he said, his voice quaking a little. “Let’s not make today most days. Please, we need your support to be able to protect you from men like these, who carried out this tragic, tragic event.”

By Friday afternoon, hundreds of residents were wearing ribbons in support of police officers. A video by The Atlanta Journal-Constitution of people lining up to hug police officers after an interfaith prayer service has been viewed more than 27 million times.

Dallas Police Sgt. Michael Mata hopes the support for law enforcement will remain strong.

“The city loves you for a day, loves you for a week” after high-profile tragedies, he said. “There once was a time when, if there was a situation, a citizen would step forward and help you. Now they pull out their cellphone because they want to be the first to put it on social media.”

Mata knew the fallen officers — Dallas Police Senior Cpl. Lorne Ahrens, Officers Michael Krol and Patrick Zamarripa, Sgt. Michael Smith and Dallas Area Rapid Transit Officer Brent Thompson — and was once Ahrens’ partner.

“He had an ear-to-ear smile,” he said. His stature seemed diminutive compared to his former 6-foot-5 partner, and the sight of them walking up to a crime scene was sometimes humorous enough to defuse the situation. “His heart was as big as he was.”

A police officer and a DART officer have been treated and released while four officers and a civilian remained hospitalized, the Dallas Morning News reported Saturday.

Although protests have continued in cities across the nation, including Atlanta, where law enforcement and protesters stared each other down for hours on Friday night, the streets of downtown Dallas have been quiet. Many people traversing the area near the shooting site on Saturday did so on bike or on foot.

Adisa Onu, who lives just down the street from where the shooting occurred and watched the massacre unfold from his 24th-floor balcony, stopped by mid-jog to shake hands with Borja and Harder, the trooper and officer tasked with guarding a portion of the crime-scene perimeter.

“I understand what the protesters are accomplishing,” Onu said. “I see them as a change agent. What happened during the protests was detrimental to the cause.”

The protest was organized to express outrage over police-involved shootings elsewhere, and support for the fallen officers hasn’t erased the tensions that spurred the march in the first place.

Dallas resident Keon Collins walked by the shooting site on Friday night, slowly and deliberately, with his middle finger raised as he walked past officers.

“My thoughts go out to the victims,” he said. “They were good people.”

His one-finger salute was meant as a statement against police brutality in general, he said.

“The police have been getting away with this for years, and they’re not going to get away with it anymore,” he said. He stressed that he does not condone the shooting but says it provides “a good lesson to the police: Stop killing.”