U.S. Steel released preliminary findings about the potential cause of Monday's deadly explosion at U.S. Steel Clairton Coke Works.

U.S. Steel spokeswoman Amanda Malkowski said in a statement on Friday that " preliminary indications lead us to believe " that the explosion happened when a gas valve was flushed in preparation for planned maintenance.

The statement said that as pressure built inside the valve, it failed, and coke oven gas filled the area. The explosion then happened when an ignition source was found.

"We want to reinforce that this investigation is in its early stages, and we will provide more information when we can," Malkowski's statement said.

At around 11 a.m. on Monday, an explosion at U.S. Steel Clairton Coke Works killed two and injured at least 10 people. The i

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