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.

Workers were pushing coke out of huge ovens and preparing for maintenance when an explosion rocked a U.S. Steel plant outside Pittsburgh, a company executive said Tuesday, a day after the blast killed two workers.

A deadly explosion rocked the U.S. Steel Clairton Coke Works plant late Tuesday morning, leaving one worker dead, one still unaccounted for, and multiple others injured. The blast was reported at 10:51 a.