CLAIRTON, Pa. -- An oven at a U.S. Steel plant near Pittsburgh exploded Wednesday, injuring 15 workers, at least two critically, and causing a fire that burned for hours afterward, emergency officials said.
The blast in the coke oven at United States Steel Corp.'s Clairton Coke Works happened around 9:30 a.m. Wednesday, Allegheny County spokesman Kevin Evanto said. Fourteen workers suffered burns and another suffered chest pains.
Everyone had been accounted for, and the cause was being investigated, union and company officials said. The Occupational Safety and Health Administration had a team of investigators on site, spokeswoman Leni Fortson said.
Neighbors said they heard alarms at the plant but didn't know at first whether it was a real emergency.
"They always play their siren," said Tiarra Williams, 17, who lives on a hill overlooking the plant. A maintenance worker died in a September 2009 explosion at the plant, which sits in a valley along the Monongahela River about 20 miles south of Pittsburgh.
Workers took lunch breaks around noon, as an Allegheny County sheriff's car sat parked at one of the entrances, along with an ambulance.
About 1,500 people work at the plant, said Wright, head of the health, safety and environment department for the United Steelworkers union.
Coke, a raw material used in steelmaking, is coal that is baked for a long time at a high temperature to remove impurities. U.S. Steel calls its Clairton plant the biggest coke manufacturing facility in the U.S. at about 4.7 million tons per year.
Two workers were in critical condition after being taken to the burn unit at West Penn Hospital, spokesman Dan Laurent said. Another was in serious condition.
Six workers were taken to UPMC Mercy, which has a burn unit, said Gloria Kreps, a spokeswoman for UPMC hospitals. She did not know what their conditions were.
Another injured worker was taken to UPMC McKeesport, and "three or four" were taken to UPMC Presbyterian, she said.
William Magyar, 44, of McKeesport, was cleaning a rental property near the plant when he said he heard alarms around 10 a.m.
"I figured it was a fire I didn't smell," Magyar said.
Elaine Lawrence, 53, whose son works at the plant, was lying on the couch at her Clairton home when her daughter told her there had been an explosion. The daughter drove her to the plant, but they weren't allowed in; they headed to a hospital, and that's when her son called.
"He said he had just passed where the explosion happened to go to the other block and suddenly he heard an explosion," Lawrence said. Martin Lawrence, 19, was not injured and remained at work, she said.
"I was real concerned, because that's my only son," she said.