

CLAIRTON: Investigators are working to determine the cause of an explosion that rocked a steel plant outside Pittsburgh, leaving two dead and more than 10 others injured, including a person who was rescued from the smoldering rubble after hours of being trapped.
The explosion sent black smoke spiraling into the midday Monday 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 in Clairton started late Monday morning. Officials said they had not isolated the cause of the blast.
The rumbling from the explosion, and several smaller blasts that followed, jolted the community about 15 miles (24 kilometers) southeast of Pittsburgh. Amy Sowers, who was sitting on her porch less than a mile from the plant, felt her house shake.
“I could see smoke from my driveway,” she said. “We heard ambulances and fire trucks from every direction.”
Sowers, 45, grew up in Clairton and has seen several incidents at the plant over the years.
“Lives were lost again,” Sowers said. “How many more lives are going to have to be lost until something happens?
Investigating the blast's cause
At a news conference, Scott Buckiso, U.S. Steel’s chief manufacturing officer, did not give details about the damage or casualties, and said they were still trying to determine what happened. He said the company, now a subsidiary of Japan-based Nippon Steel Corp., is working with authorities.
The county medical examiner's office identified one of the victims as Timothy Quinn, 39.
The Allegheny County Police Department said five people were hospitalized in critical but stable condition Monday night, and five others had been treated and released. Multiple individuals also were treated for injuries at the scene, but the department said it did not have an exact number.
According to the company, the plant has approximately 1,400 workers.
In a statement, the United Steelworkers, which represents many of the Clairton plant’s workers, said it had representatives on the ground at the plant and would work to ensure there is a thorough investigation.
David Masur, executive director of PennEnvironment, an environmental group that has sued U.S. Steel over pollution, said there needed to be “a full, independent investigation into the causes of this latest catastrophe and a re-evaluation as to whether the Clairton plant is fit to keep operating.”
U.S. Steel CEO David B. Burritt said the company would investigate.
It's not the first explosion at the plant. A maintenance worker was killed in a blast in September 2009. In July 2010, another explosion injured 14 employees and six contractors. According to online OSHA records of workplace fatalities, the last death at the plant was in 2014, when a worker was burned and died after falling into a trench.
After the 2010 explosion, the Occupational Safety and Health Administration fined U.S. Steel and a subcontractor $175,000 for safety violations. U.S. Steel appealed its citations and fines, which were later reduced under a settlement agreement.
In February, a problem with a battery at the plant led to a “buildup of combustible material” that ignited, causing an audible “boom,” officials said. Two workers received first aid treatment but were not seriously injured.