Thousands head home after Tennessee train fire forced evacuation

About 5,000 residents evacuated after the derailment of a freight train carrying flammable and toxic gas in eastern Tennessee were allowed home on Friday as investigators looked into the cause of the fiery accident.

Authorities were examining the black box from the CSX Corp train that derailed with one tank car bursting into flames at midnight Wednesday in Blount County, near Maryville, Tennessee.

The tank car fire was extinguished by late Thursday, CSX said. The car was loaded with about 24,000 gallons of acrylonitrile, a hazardous material used in manufacturing plastics and other industrial processes.

Nearly all of the acrylonitrile escaped during the fire, a CSX official said at a noon press conference.

Noxious fumes sent more than 80 people to hospital, including 10 law enforcement officers who were kept overnight, said Blount County Sheriff's spokeswoman Marian O'Briant.

The U.S. Environmental Protection Agency was testing air, soil and water samples and "so far everything is looking good there," O'Briant said.

Residents were advised not to use well water until final test results are released later on Friday, county officials said. They said about 200,000 air monitoring locations showed no significant contamination.

After about 36 hours, all of the 5,000 residents who were evacuated from a 1.5-mile radius of the derailment were allowed to return home. Blount County has urban and rural areas and is home to part of the Great Smoky Mountains National Park.

The cause of the derailment is under investigation by officials of the Federal Railroad Administration and CSX, the company said.

The train was en route from Cincinnati to Waycross, Georgia, when the tank car derailed, CSX said. The train was made up of two locomotives and 57 cars, including 27 carrying hazardous materials, according to the company.

By midday Friday, the locomotives and all the cars had been removed except for the burned car and one coupled to it that also was carrying acrylonitrile, a CSX official said.

A handful of the evacuees spent the night at a Red Cross shelter set up at a nearby high school, while the others stayed with friends, family and at area hotels. CSX said it was offering displaced residents lodging, drinking water and other assistance.

(Writing by Barbara Goldberg in New York; Editing by Ian Simpson, Jeffrey Benkoe and Peter Galloway)