An explosion rocked the U.S. Steel Clairton Coke Works facility near Pittsburgh Monday, leaving people trapped beneath the rubble, officials said.

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

An explosion at a U.S. Steel plant south of Pittsburgh killed two people and injured 10 others. The CEO has vowed to find out what caused Monday’s blast while union officials say representatives will work to ensure a thorough investigation.