Authorities say the fire that caused the deadly explosion at a Texas fertilizer plant in 2013 was a criminal act.
Federal and state investigators said Wednesday that they're investigating who was responsible for causing the fire at the West Fertilizer Co. facility on April 17, 2013, in the town of West.
The fire caused ammonium nitrate to ignite, triggering a massive explosion that killed 15 people, injured hundreds and left part of the small town in ruins.
The U.S. Chemical Safety Board and the state fire marshal's office previously issued reports faulting the storage of the fertilizer, emergency response and other factors contributing to a blast, which registered as an earthquake of magnitude 2.1.
But authorities hadn't previously indicated what specifically caused the fire.