Federal officials say the 2013 explosion at the West Fertilizer Company facility in West, Texas started from an intentionally set fire. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives announced the findings Wednesday stemming from a re-enactment of the fire performed at a research lab. While the ATF did not identify any suspects, the federal agency is offering a reward of up to $50,000 for information leading to an arrest. A criminal investigation has been underway since shortly after the blast, according to the Dallas Morning News. The explosion killed 15, injured 300, and leveled a neighborhood in West, Texas, about 75 miles south of Dallas. About a month after the blast, the fire marshal offered three possible causes of the fire, faulty electrical wiring, a spark from a golf cart parked in a shed adjacent to the bin holding the fertilizer, or arson.