Rescuers found one of the two people who were missing after an explosion at the US Steel Clairton Coke Works plant.

CLAIRTON, Pa. (AP) — An explosion Monday at a U.S. Steel plant near Pittsburgh has left people trapped under the rubble, with emergency workers on site trying to rescue them, an official said. There are no confirmed fatalities yet at the Clairton Coke Works, said Abigail Gardner, director of communications for Allegheny County.

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.