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.

U.S. Steel's Clairton Coke Works — long flagged for safety and environmental concerns — is under fresh scrutiny after an explosion killed two workers this week. The big picture: Once a defining part of the Pittsburgh region's economy,

The U.S. Steel plant in Clairton, Pa., where an explosion killed two workers and injured 10 on Monday, has a history of maintenance issues, explosions and environmental violations.