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,

The explosion, followed by several smaller blasts, could be felt in the nearby community and prompted county officials to warn residents to stay away from the scene so emergency workers could respond.

Two people are dead and 10 others injured after an explosion at U.S. Steel’s Clairton Coke Works near Pittsburgh. The recovery operation has ended, and the cause is under investigation.