Luke Air Force Base officials say a student pilot from Taiwan is feared dead after an F-16 fighter jet crashed in northwestern Arizona.
"Luke AFB officials are working closely with local authorities in a search and rescue operation," base officials said in a statement. "Due to the remote location and rugged terrain, the status of the pilot is unknown."
They say crews were still looking for the man late Thursday afternoon, and signs indicate that he didn't survive.
The pilot's name wasn't immediately released.
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Base officials say the pilot was six months into a training program at Luke, which is a major training base for the Air Force and foreign military services.
They say the crash occurred about 8:30 a.m. Thursday as the student pilot and an instructor in another F-16 were engaged in air-to-air combat training.
A Yavapai County Sheriff's Office spokesman said the crash site was found south of Bagdad by a helicopter crew about four hours after the jet went down.
The area is sparsely populated. Bagdad is about 85 miles northwest of Luke, which is located in the Phoenix suburb of Glendale.
Base officials said the jet was assigned to the 56th Fighter Wing at Luke, which is a major pilot-training base for the Air Force and foreign military services.
The cause of the crash wasn't known, and the wing's commander established an interim safety board to conduct a preliminary investigation, Luke officials said.
Several civilian agencies sent aircraft and personnel in response to word of the crash.
The Yavapai County Sheriff's Office sent a helicopter to look for the crash site, while the Arizona Department of Public Safety spokesman Quentin Mehr sent troopers, a rescue helicopter and explosive ordinance and hazardous material teams, spokesmen said.
Recent previous crashes involving F-16s from Luke included one on a training mission in southern New Mexico. That pilot ejected safely.
So did an instructor pilot and a student pilot in June 2013 after their two-seat F-16 hit several birds during takeoff from Luke. The jet crashed in a farm field.
An Air Force investigation report said the instructor pilot was at fault because he made a rapid climbing turn after the bird strike, robbing the plane of airspeed and the ability to recover and return to the base.