A man who was injured in an explosion at a MarkWest energy facility in Pennsylvania last week has died.
The Allegheny County Medical Examiner's Office says 61-year-old Jeffrey Fisher, of Salem, West Virginia, died Tuesday at a hospital burn unit.
Fisher was one of four injured in the explosion and subsequent fire at the facility in Chartiers Township Dec. 13.
The conditions of the other three people have not been released.
MarkWest previously said the explosion happened near two temporary tanks. The company gathers and processes natural gas and stores chemicals related to fracking.
Parent company spokesman Jamal Kheiry said Wednesday they are "deeply saddened" about Fisher's death.
He says the company is working with federal, state and local officials to investigate the explosion.