Workers were heating coal and preparing for routine maintenance when an explosion rocked a U.S. Steel plant outside Pittsburgh

The mill, which is part of the recent merger between U.S. Steel and Nippon Steel, has faced scrutiny from federal and local regulators.

“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.

A devoted dad has been identified as one of the two steel workers killed from an explosion at a Pennsylvania steel plant on Monday, officials said.

The explosion at U.S. Steel's Pittsburgh-area plant has reignited debate about its future. The plant, part of a long-standing steelmaking tradition in the Mon Valley, faces uncertainty despite recent investments.

Donald Trump said National Guard troops will be deployed to Washington, D.C., and Pam Bondi will "take command" of local police.