Allegheny County Emergency Services said a fire at the plant in Clairton started late Monday morning. Officials said they had not isolated the cause of the blast.

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.

U.S. Steel officials have released new details about the moments leading up to an explosion at the Clairton plant that killed 2 and injured 10.