Explosions at a U.S. Steel plant near Pittsburgh left one dead and dozens injured or trapped under the rubble Monday, with emergency workers on site trying to rescue victims, officials said.

The explosions sent black smoke spiralling into the midday sky in the Mon Valley, a region of the state synonymous with steel for more than a century. An Allegheny County emergency services spokesperson, Kasey Reigner, said one person died and two were currently believed to be unaccounted for. Multiple other people were treated for injuries, Reigner said.

Allegheny County Emergency Services said a fire at the plant started around 10:51 a.m. The explosions sent a shock through the community and led to officials asking residents to stay away from the scene so emergency workers could respond.

“It felt

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