“It is with profound sadness that I share with you that the U. S. Steel colleague who had been unaccounted for has been located and confirmed deceased, following an extensive search and rescue effort," David Burritt, the company's CEO, said in a statement. At least 10 people were injured in the blast, officials said.

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.