The preliminary findings say how the company believes the explosion occurred. A union statement cautioned the investigation is in its early stages.

The deadly explosion at Clairton Coke Works near Pittsburgh occurred when a gas valve was flushed before planned maintenance, ...

Allegheny County is increasing air quality monitoring after an explosion at a U.S. Steel plant south of Pittsburgh killed two ...

U.S. Steel released preliminary findings about the potential cause of Monday's deadly explosion at U.S. Steel Clairton Coke ...

The explosion happened when workers were flushing a gas valve in preparation for maintenance on two of the plant's coke oven ...

U.S. Steel says preparations for a routine maintenance task may have led to an explosion at a U.S. Steel coal-processing ...