CLAIRTON, Pa. (TNND) — An investigation is ongoing after two people were killed and 10 were injured in an explosion at a U.S. Steel plant near Pittsburgh on Monday, leaving behind smoldering rubble and plumes of black smoke.

A fire Monday at the US Steel mill, 20 miles south of Pittsburgh, hurt 10; 1 person is missing. Residents within a mile are advised to stay indoors.

One person has died, one person is unaccounted for and at least 10 are injured following an explosion at a U.S. Steel plant near Pittsburgh, Allegheny County Police Assistant Superintendent Victor Joseph said at a press conference Monday afternoon.