Ten people were hospitalized after the blast at a coke plant in Clairton, Pa., near Pittsburgh. One person who had been missing was found dead late on Monday.

An explosion at a U.S. Steel plant near Pittsburgh left one dead and dozens injured or trapped under the rubble Monday, with emergency workers on site trying to rescue victims, officials said. The explosion sent black smoke spiralling into the midday sky in the Monongahela Valley,

In Pennsylvania, the blast at a steel plant has killed two people. Officials say they are still investigating the cause. One worker describes what he saw and heard during the moment of the explosion.

The chief of the Allegheny County Emergency Management recounted for reporters the conditions inside the Clairton Coke Works plant following Monday's explosion.