Robert Champion, special agent in charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives Dallas field office, told reporters investigators have not ruled out the possibility the explosions at West Fertilizer Co. resulted from a fire that may have been set intentionally, NBC News reported.
Investigators said the fire, which originated in a fertilizer and seed building called the "seed room," may have been a case of arson, or it may have resulted from an electrical system failure. They said they could not rule out a compromised golf cart battery as a possible cause but the battery has not been recovered, NBC reported.
Investigators have ruled out other possible causes, including weather, spontaneous ignition, a larger electrical system, ammonium compounds used to make fertilizer, and smoking, the report said.
The explosions devastated a 37-square-block area and left a crater 93 feet wide and 10 feet deep, Champion said.
Authorities said they would not provide many details of the investigation to date because the matter is being treated as a criminal case.