BLACKSBURG, Va. — A spokesman for an auto parts supplier says four people have been injured in an explosion at the company’s plant in Virginia.

Jim Burke, spokesman for Federal-Mogul Corp. in Southfield, Mich., said the injured were employees of a contractor that was conducting routine duct work cleaning.

Eric Earnhart, a spokesman for Roanoke Carilion Hospital, said two critically injured patients were flown to Wake Forest University Baptist Medical Center in Winston-Salem, N.C.

George Ward, lead security officer at Lewis Gale Montgomery Hospital, said two patients were treated there for relatively minor injuries.

The Blacksburg plant is one of 107 facilities operated by Federal-Mogul worldwide. It specializes in bearings.