Workers were pushing coke out of huge ovens and preparing for maintenance when an explosion rocked a US Steel plant outside Pittsburgh, a company executive said Tuesday, a day after the blast killed two workers.

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.

Authorities said 10 other workers required hospital treatment — including five listed in critical but stable condition — after an explosion Monday morning at the U.S. Steel Clairton Coke Works. The cause of the blast has not been determined.