An explosion at a U.S. Steel plant near Pittsburgh on Monday has killed one person and injured multiple others, with at least two people missing, police said, as fire crews could be seen battling flames while heavy smoke rose from the facility.

An explosion Monday at a U.S. Steel plant near Pittsburgh has left people trapped under the rubble, with emergency workers on site trying to rescue them, an official

A rescue operation was underway for people trapped under rubble, while a cause for the explosion has not been confirmed.