Explosion at steel plant leaves one dead and dozens hurt

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

The explosion sent black smoke spiralling into the midday sky in the Monongahela 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 in the explosion and two were currently believed to be unaccounted for.

Multiple other people were treated for injuries, Ms Reigner said.

Allegheny County Emergency Services said a fire at the plant started around 10.51am.

The explosion 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 like thunder,” Zachary Buday, a construction worker near the scene, told WTAE-TV.

“Shook the scaffold, shook my chest, and shook the building, and then when we saw the dark smoke coming up from the steel mill and put two and two together, and it’s like something bad happened.”

Dozens were injured and the county was sending 15 ambulances, on top of the ambulances supplied by local emergency response agencies, Ms Reigner said.