A massive explosion at the U.S. Steel Clairton Coke Works in Pennsylvania has prompted a mass casualty incident, with emergency crews rushing to the scene. The blast, which occurred at the coking facility near Pittsburgh, has reportedly left multiple people trapped under rubble.

EMS units and other emergency resources have been deployed as rescue operations are underway. Local authorities have not yet confirmed the number of casualties or the cause of the explosion, but witnesses describe a powerful blast that shook surrounding neighborhoods.

The Clairton Coke Works is the largest coke manufacturing facility in the United States, producing fuel for steelmaking. Officials are urging residents to avoid the area as emergency responders work to secure the site and assist victims.