Two Republic of Korea Air Force (RoKAF) KAI KT-1 Woongbi trainer aircraft, operated by 3 Training Wing, collided mid-air and crashed into a mountain near Sacheon Air Base/Airport (HIN/RKPS). Three pilots died and one survived with serious injuries.
The crash happened about 6 km (3.7 miles) south of the KT-1 airplane base in the southeastern city of Sacheon, at about 1:37 p.m.(0437 GMT), the air force said.
“Despite their attempts at an emergency escape … all of the two student pilots and two flight instructors aboard the two planes died,” it said in a statement.
The air force will “check the exact situation of damage and investigate the cause of the accident”, the statement said.
More than 30 firefighters and emergency responders were dispatched to the crash site, the Yonhap news agency reported.
The crash is one of several incidents involving South Korean air force jets this year.
In January, a pilot was killed in an F-5 fighter jet crash.
That accident took place shortly after the country grounded its entire fleet of advanced F-35 fighter jets following a major systems malfunction on one plane that forced a dramatic emergency landing.