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.

The explosion, followed by several smaller blasts, could be felt in the nearby community and prompted county officials to warn residents to stay away from the scene so emergency workers could respond.

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,