Authorities on Wednesday announced that a massive fertilizer plant explosion more than three years ago was caused by an intentional fire.
The blast at the plant in West, Texas, on April 17, 2013 killed 15 people — including 12 first responders — injured 300 and destroyed more than 500 homes.
Federal regulators said that West Fertilizer had improperly stored large amounts of potentially dangerous chemicals, and the Obama administration subsequently launched an effort to overhaul safety regulations at the nation's chemical plants.
But the Bureau of Alcohol, Tobacco, Firearms and Explosives this week said that it ruled out "all viable accidental and natural fire scenarios" following hundreds of interviews, reviews of on-site evidence and camera footage and "extensive scientific testing."
"This was a criminal act," ATF special agent Robert Elder said, according to the Associated Press.
The bureau offered a $50,000 reward for information leading to those responsible for setting the fire.
