Investigators are working to determine the cause of an explosion that rocked a steel plant outside Pittsburgh, leaving two dead and more than 10 others injured, including a person who was rescued fro...

Preparations for a routine maintenance task may have led to an explosion at a U.S. Steel coal-processing plant near Pittsburgh that left two dead and sent 10 to hospitals, the company said Friday.

Their assessments will look at pollutants like Volatile Organic Compounds, PM2.5 and sulfur dioxide.