A train hauling sulfuric acid overturned early Wednesday, forcing the evacuation of about 250 southern Illinois homes in a half-mile radius of the accident, authorities said.

There were no immediate reports of injuries.

Emergency crews were determining whether any of the 92,000 pounds of sulfuric acid it was carrying had leaked, said David Searby, operations officer for Du Quoin Emergency Services. The chemical can burn skin and trigger asthma attacks.

"Obviously, we have to approach this very slowly," Searby said.

Jim Kvedaras, a U.S. spokesman for Toronto-based Canadian National, said the train derailed just before 2 a.m. at a switching site on the company-owned tracks. He said none of the sulfuric acid was known to have leaked.