Explosion at US Steel plant in Pennsylvania leaves dozens hurt and people trapped under rubble

An explosion Monday at a U.S. Steel plant near Pittsburgh has left dozens injured or trapped under the rubble, with emergency workers on site trying to rescue them, officials said.

There are no confirmed fatalities at the Clairton Coke Works, said Abigail Gardner, director of communications for Allegheny County. The explosion sent black smoke spiralling into the midday sky in the Monongahela Valley, a region synonymous with the state for more than a century.