Two workers died and at least 10 people were injured after multiple explosions at the U.S. Steel Clairton plant.

An explosion at a U.S. Steel plant south of Pittsburgh killed two people and injured more than 10 others. The CEO has vowed to find out what caused Monday’s blast while the workers’ union says it will make sure there’s a thorough investigation.

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.