Fifteen freight train cars derailed in an industrial area of Maryland this afternoon, causing an explosion, the collapse of several buildings and leaving one person in serious condition, according to authorities.
The CSX train derailed in the White Marsh, Md., area at about 2 p.m., according to officials.
"Several buildings collapsed at the site of the train derailment," Baltimore County public safety information specialist Louise Feher told ABCNews.com.
An overturned garbage truck could be seen at the scene and the driver was the injured person, according to the Baltimore County Police and Fire Department.
The truck driver was removed from the truck and taken to a hospital. The driver was in serious but stable condition, authorities said.
Police told ABC News tonight that the truck was used for garbage or waste disposal.
The train and truck collided, but officials have not yet provided details on the collision or whether the collision caused the derailment. Police said that there was not yet anything to indicate foul play.
Two CSX train employees were not injured, officials said.
"There was an explosion and there was smoke," she said.
Officials did not immediately know the cause of the explosion.
Baltimore Fire Chief John Hohman told a news conference that 15 cars derailed and two cars were ablaze that contained the chemicals terephthalic acid, which is used in plastics, and fluorosilicic acid.
A third car carrying the dangerous chemical sodium chlorate was not on fire, he said.
A CSX official later clarified the situation.
"Four cars contained terephthalic acid," the official, Kristin Seay, said in a written statement. "One car contained fluorosilicic acid -- that rail car was empty but CSX lists it as a 'residue car' because the car may still contain traces of the product."
Feher said fire units and hazmat officials were on the scene, although, officials said, there were no hazardous materials involved.
Authorities asked people in a 20-block area to stay away and anyone with asthma to stay indoors as a precaution. The nearby Pulaski Highway was closed in both directions. Authorities tonight extended the non-mandatory evacuation "suggestion" to an additional 60 homes in neighborhoods west of incident.
Long-term exposure to terephthalic acid can cause respiratory problems, authorities said, citing a state of New Jersey report.
Witnesses in the area told ABC News' Baltimore affiliate WMAR-TV that businesses near the scene shook and "mushroom cloud" could be seen.
Richard Bosley, a man who was working in the area, told WMAR-TV that he could smell and taste fumes in the air.
Contributing reporting by ABC News' Howard Price.