http://www.nbcnews.com/news/us-news...plant-explosion-was-criminal-act-feds-n572231 A 2013 fertilizer plant blast in West, Texas, that killed 15 people and injured 160 others was caused by a "criminal act," federal officials said Wednesday. The Bureau of Alcohol, Tobacco, Firearms and Explosives revealed the findings of its investigation of the deadly fire and explosion at the West Fertilizer Co. on April 17, 2013. ATF Special Agent Robert Elder said the agency is offering a $50,000 reward to help find the person who committed the "crime," which was determined to be the reason for the explosion after "we ruled out all accidental and natural causes." But he couldn't say why someone would have set the fire. "I think it's too early to speculate on murder charges," Elder added. Play Ticking time-bomb next door? 1:26 No arrests have been made, but more than 400 interviews have been conducted amid the investigation, Elder said. Among those who dead in West were 10 first responders and two volunteers who were killed while fighting the initial fire before the blast occurred just before 8 p.m. local time. The explosion flattened the rural farming community of 2,800 people, just north of Waco, turning it into rubble as people tried desperately to flee the horrific scene. The event occurred during the same week the nation was gripped by the Boston Marathon bombing.