WASHINGTON (AFP) - A freight train plowed into a garbage truck and derailed on Tuesday near the US city of Baltimore, triggering a fire and a massive explosion that injured a driver and was reportedly felt for kilometres.
Television footage showed several train cars lying on their side and engulfed in flames, along with the mangled remains of the truck that may have tried to cross the tracks as the train passed.
Thick black smoke billowed out from some of the derailed train cars and stretched across the area, with authorities stressing that while some chemicals including a fluoride material were burning, they were not especially dangerous.
"They're not toxic inhalants," Baltimore County Fire Chief John Hohman told reporters, adding that 15 cars derailed and two were on fire and that officials would likely allow the fire to burn into the night.
CSX Transportation, the cargo carrier that operates the train, said in a statement that one of the cars that derailed contained sodium chlorate, which is classified by the US Transportation Department as a hazardous material.
"That car is not burning at this point in time," Mr Hohman said.
As a precaution, authorities ordered the evacuation of a 20-block area around the accident.
The force of the explosion, on a freight rail line in the Baltimore suburb of Rosedale, Maryland, 64km north-east of the US capital Washington, appeared to have blown away the facade of some warehouses near the tracks.
It also blew out windows at Atlantic Tire several hundred feet from the accident site, according to sales associate John Perrigan who said he witnessed the blast.
"The force of air that hit me in the face was incredible," he told AFP by telephone. "If nobody got hurt it's amazing." Authorities did say that one person was being treated in hospital.
"2 employees on CSX train not injured - truck driver is the person taken to shock trauma in serious condition," the Baltimore County Police and Fire Department said in a message posted on Twitter.
The incident is the second major train accident in as many weeks along the busy northeast corridor.
Earlier this month two commuter trains were involved in a rush-hour collision between New York City and New Haven, Connecticut, injuring more than 70 passengers and severing a key rail link.
Transportation inspectors are investigating that crash, and also announced a probe of the Maryland accident.