A freight train carrying a corrosive chemical derailed in a Pittsburgh suburb early Monday, sending several cars into a river and forcing the evacuation of 200 residents, officials said.

Thirteen of the Norfolk Southern (search) train's 83 cars derailed at about 5:30 a.m. in East Deer Township.

One of several cars that ended up in the Allegheny River (search) leaked an unknown amount of anhydrous hydrogen fluoride (search), a chemical used in steelmaking, said Betsy Mallison, a state Department of Environmental Protection spokeswoman. The tanker can hold up to 15,000 gallons.

There were no reports of injuries and Mallison said no significant environmental impact was expected. Nearby residents were evacuated as a precaution and it wasn't clear when they would be allowed to return home, she said.

Water departments downriver of the accident were notified as a precaution, Mallison said.

Some roads in the area also were closed.