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

Don Furko is a mechanical maintenance planner who this week reached his 25th anniversary at the plant. He was working in a different area with the blast took place.

Rescuers were continuing to search for one missing worker at the Clairton Coke Works more than five hours after mid-morning explosions rocked the Mon Valley plant. The blasts killed one person and injured 10.