A small single-engine plane crashed in the U.S. state of Arizona on Saturday, and the pilot\'s conditions remained unknown, authorities said. The plane, which was identified as an experimental Vans RV-7A, crashed in Surprise, a city in northern Arizona. Its wreckage was spotted approximately 25 miles (40 km) northwest of Sky Harbor International Airport, Phoenix, Federal Aviation Administration (FAA) spokesman Ian Gregor said. The pilot of the ill-fated aircraft at round 1 p.m. local time (0500 GMT) radioed air traffic controllers at Luke Air Force base, saying that he had lost control of the plane and was going down, according to the spokesman. The pilot\' fate remained unknown, authorities said. It\'s not clear at this moment if there is any other person aboard the small two-seat airplane. The FAA and National Transportation Safety Board will look into the cause of the crash.