A CSX freight train crashed into a trash truck, derailed and caught fire Tuesday in a Baltimore suburb, setting off an explosion that rattled homes at least a half-mile away and sent a plume of smoke into the air that could be seen for miles.

In the third serious derailment this month, the dozen or so rail cars, at least one carrying hazardous materials, went off the tracks at about 2 p.m. in Rosedale, a suburb east of Baltimore. A hazardous materials team responded, but Baltimore County Executive Kevin Kamenetz said at a news conference that no toxic inhalants were being released. Officials did not order an evacuation.

By nightfall, the hazmat team had left, meaning there was no more danger posed from the chemicals in the rail car, said Baltimore County police Capt. Bruce Schultz.

The truck driver, 50-year-old John J. Alban Jr., was in serious condition Tuesday night, a hospital spokeswoman said. Two CSX workers aboard weren’t hurt.

Dale Walston said he lives about a half-mile away and that he thought he could smell chemicals.

“It shook my house pretty violently and knocked things off the shelves,” he said in an email.

The face of one warehouse near the train tracks was blown off.

Even hours after the blast, the thick plume of black smoke could be seen for miles and had drifted and covered the eastern part of Baltimore. Later, the smoke that was left had lightened considerably, changing from black to gray, though the fire wasn’t yet extinguished as of 9 p.m.

CSX spokesman Gary Sease said in an email that one of the cars was carrying sodium chlorate, which the Department of Transportation classifies as a hazardous material. However, Baltimore County Fire Chief John Hohman said the chemical was not in any of the cars that were still burning into the evening. The bleaching agent is used in making paper.

Nick Materer, an Oklahoma State University chemist, said sodium chlorate, when combined with fuel, makes a more volatile mixture. “When you mix them together and add fire, they go boom,” he said in a phone interview.

Exactly what triggered the explosion was being investigated, and Hohman said firefighters told residents of about 70 nearby homes that they could leave if they wanted to and shelter would be provided.

Two warehouses were heavily damaged by the explosion and other buildings were harmed, but none collapsed, as was thought earlier, Hohman said.

Kevin Lindemann, 29, a salesman for industrial pipe supplier Baltimore Windustrial near the tracks, said he and about 10 co-workers felt the ground shake, ran to a window and saw several cars on their sides and flames he estimated at 50 feet high.

“You could feel the heat as soon as you walked out the door,” Lindemann said.

“We kind of panicked pretty quick,” he said. “We didn’t wait around to see what was happening. So as soon as we saw the flames I took a quick picture and got in my truck and drove away.”

Everyone left the building and drove several blocks away. Then they heard the explosion, five to 10 minutes after the derailment, he said.

“Even like three blocks away, it was loud. I mean, it just about took you to your knees,” Lindemann said.

The National Transportation Safety Board and the Federal Railroad Administration were sending teams to investigate Tuesday’s crash of the 45-car train en route from Selkirk, N.Y., to Waycross, Ga.

Police also planned to investigate the circumstances that led to the track collision, but it was not clear what, if any, charges the truck driver or anyone would face, said Baltimore County spokeswoman Elise Armacost.

Late Tuesday evening, Robert Sumwalt of the National Transportation Safety Board said the accident occurred at a private crossing where the only marking was a stop sign. He said it wasn’t clear why the truck was crossing the tracks or whether it was authorized to be there.