Suspicious device” explodes at Nogales power plant Jun 11 2014 in Featured Articles, Incident Reports by Homeland Security NTARC News A makeshift bomb exploded at a Nogales, Arizona power plant Wednesday, rupturing a large fuel tank and prompting the FBI and federal bomb experts to respond. Local officials were alerted at 9:30 a.m. to a call of “suspicious activity” at the UniSource Energy Services Valencia Plant. An explosion had ruptured a diesel storage tank and caused what Nogales Police Lt. Carlos Jimenez described as a relatively small spill that was confined to the immediate area.