U.S. Steel on Friday pinned the blame for the deadly explosion Monday at the Clairton Coke Works on a valve failure that led to coke oven gas igniting, according to the company’s preliminary findings.

U.S. Steel says it believes a gas valve failure led to the explosion Monday morning at its Clairton Coke Works, in which two workers died and 10 others were injured.

U.S. Steel has released new details on what investigators believe caused the explosion at the Clairton Coke Works plant that killed 2 people and injured 10 others.