An explosion occurred Monday at a steel factory in Clairton, Pennsylvania, authorities said. A spokesperson for Allegheny County said a rescue operation was underway at U.S. Steel Clairton Coke Works for people trapped under the rubble.

Two people have died and 10 are injured following an explosion at a Pennsylvania steel plant on Monday, Allegheny County police said.

The explosion sent black smoke spiraling into the midday sky in the Mon Valley, a region of the state synonymous with steel for more than a century.