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.

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.

At least one person has died, and one person remains unaccounted for, while at least 10 people have been injured following multiple explosions at the U.S. Steel Clairton plant.