Air Force drone crashes in Nevada, no injuries LAS VEGAS (Reuters) - A $53.5 million, unmanned Air Force drone crashed at a remote location in Nevada during a nighttime training exercise, but there were no injuries, authorities said. Air Force officials said the MQ-9 Reaper aircraft came down on the Nevada Test and Training Range west of Hiko, in south-central Nevada, on Wednesday night. The cause of the crash has not been determined. "We're really grateful that nobody was injured," said Benjamin Newell, a spokesman at Nellis Air Force Base, in Las Vegas. A board of officers will investigate the accident, he added. Described as a "remotely piloted hunter/killer weapon system" on the Air Force website, the drone was participating in a combat training mission as part of the U.S. Air Force Weapons School Mission Employment phase. The MQ-9 is one of a group of remotely piloted planes operated out of Creech Air Force Base, about 45 miles northwest of Las Vegas. The aircraft, which has a 66-foot wingspan and is 36 feet long, cost $53.5 million to build in 2006 and is manufactured by General Atomics Aeronautical Systems, Inc., of San Diego. Figures on the number of previous accidents involving such aircraft were not immediately available. Editing by Cynthia Johnston and Stacey Joyce