Investigators have confirmed that ammonium nitrate was the trigger for the explosion at a West, Texas, fertilizer plant last month that left 14 people dead and some 200 injured, according to the Texas state fire marshal’s office.
The actual cause of the fire and subsequent blast at the West Fertilizer facility is still being determined, investigators said.
The fire marshal’s office has been leading the investigation of the April 17 blast, along with the federal Alcohol, Tobacco, Firearms and Explosives agency (ATF).
The blast caused an estimated $100 million in damages to homes, businesses and schools near the fertilizer plant, and killed several firefighters and other first responders who rushed to the scene of a fire at the fertilizer plant.
Ammonium nitrate is a dry fertilizer mixed with other fertilizers such as phosphate and applied to crops to promote growth. It can be combustible under certain conditions, and was used as an ingredient in the Oklahoma City bombing in 1995 that left 168 people dead.