WHITE MARSH, Md. (AP) -- The fire chief says no toxic inhalants are burning at the site of a train derailment outside Baltimore.
Baltimore County Fire Chief John J. Hohman said at a news conference Tuesday that fire crews would let the fire on two remaining cars burn out.
CSX spokesman Gary Sease says in an email that sodium chlorate is on one of the trains.
He says the Department of Transportation classifies it as a hazardous material.
But Hohman says the chemical is not toxic when inhaled and fire officials did not order an evacuation.
They did encourage anyone within 20 blocks who can see the smoke to leave though.
The derailment in White Marsh led to an explosion that rattled homes at least a half-mile away and collapsed nearby buildings.
UPDATE (WKOW) --- A freight train derailed in an industrial area of Maryland causing an explosion and the collapse of several surrounding buildings.
The CSX train derailed in the White Marsh area at around 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.
Feher said that there were no initial reports of injuries, but said the situation is still fluid.
"There was an explosion and there was smoke," she said. Officials do not yet know the cause of the explosion. It was not immediately known what the train was hauling. Feher said fire units and hazmat officials were on the scene, although officials said there were no hazardous materials involved..
Aerial footage showed a thick cloud of black smoke billowing from the scene and at least four train cars that had come off of the rails.
The area around the derailed train has been evacuated, Feher said. Nearby Pulaski Highway has been closed in both directions.
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.
(WKOW) -- CNN is citing a Baltimore County, Maryland firefighter as saying one person is believed to be trapped after a train derailment and fire in Rosedale, near Baltimore.
The news network is also reporting a police officer as saying a truck was involved in the derailment and that the scene is a hazardous material situation. Officials have evacuated a half-mile area around the crash site.