A second person has died after an explosion tore through a Pennsylvania steel plant on Monday, local officials have confirmed, BBC reported.

The body was discovered after a search operation which stretched into the evening at the US Steel Clairton site outside Pittsburgh.

Local police earlier confirmed that one other person had died and 10 others were injured in a large explosion which destroyed part of the plant.

An order instructing residents within a one-mile radius of the site to keep their windows and doors closed over air pollution fears triggered by the resulting fire was lifted on Monday evening. The cause of the blast is yet to be confirmed and an investigation is under way, according to BBC.