At least two U.S. Air Force pilots died on Thursday in a training accident at Vance Air Force Base in Oklahoma. The status of two other personnel involved in the accident were unknown.

The incident occurred at 9:10 a.m. CST in a training area about 85 miles north of Oklahoma City, FOX news reported. Two T-38 Talon aircraft were involved in the accident. Each aircraft, used to train pilots to fly more sophisticated fighter aircraft and bombers, can carry a pilot and an instructor.

Emergency crews from the base were helping with the treatment of casualties and the recovery of the missing airmen and their aircraft. The identity of the pilots were not released by the U.S.A.F, pending notification of next of kin.

The nimble single-engine jet T-38 Talon, which made its service debut on 17 March 1961, is used as a training aircraft by the U.S. Air Force, the U.S. Navy and NASA. Manufacturing of the aircraft ceased in 1972.

The T-38 Talon is the premiere trainer for jet pilots US Air Force