CLAIRTON, Pa, Aug 12, (AP): An explosion at a US Steel plant near Pittsburgh left two dead and sent at least 10 to hospitals Monday and heavily damaged the sprawling facility, officials said. One worker was found alive in the wreckage hours after the explosion sent black smoke spiraling into the midday sky in the Mon Valley, a region of the state synonymous with steel for more than a century.

Allegheny County Emergency Services said a fire at the plant started around 10:51 a.m. The explosion, followed by several smaller blasts, could be felt in the nearby community and prompted county officials to warn 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.” At a news conference, Scott Buckiso, US Steel’s chief manufacturing officer, did not give details about the damage or casualties, and said they were still trying to determine what happened.

US Steel employees "did a great job” of going in and rescuing workers, shutting down gases and making sure the site was stable. Buckiso said the company, now a subsidiary of Japan-based Nippon Steel Corp., is working with authorities ? US Steel CEO David B. Burritt said the company would thoroughly investigate the cause.

"I end every meeting and every message with the words, ‘Let’s get back to work safely.’ That commitment has never been more important, and we will honor it,” he said in a statement. Allegheny Health Network said it treated seven patients from the plant, and discharged five within a few hours. University of Pittsburgh Medical Center said it is treating three patients at UPMC Mercy, the region’s only level one trauma and burn center.

Clairton resident Amy Sowers was sitting on her porch, located less than a mile from the plant, and felt her house shake from the blast. "I could see smoke from my driveway,” she said. "We heard ambulances and fire trucks from every direction." Sowers, 49, decided to leave the area after she said she smelled a faint smell in the air. Sowers, who grew up in Clairton, has seen several incidents at the plant over the years. Despite health concerns, Sowers said many residents cannot afford to leave.