A South Korean Air Force F-5 fighter jet on Friday crashed into waters off the country's west coast, killing two pilots, Air Force officials said.

The fighter took off at around 09:43 a.m. local time and disappeared at around 10:33 a.m. local time near a base in the coastal city of Gangneung, north of the capital Seoul, during a return trip from a routine training mission, the officials said.

A search operation was immediately launched after the jet went missing. Several helicopters and patrol vessels were sent by the Air Force and the Coast Guard to the crash site, some 1.8 km from the base, the officials added.

Bodies of the two pilots onboard were recovered later. One of them was found knotted in a parachute partly opened, and another was wound by ropes of the parachute. Wreckate of the jet was also found scattered in the waters.

Some experts said the evidence showed that the pilots had tried to escape by using the ejection system, so there is a high possibility of a technical fault rather than flight illusion.

The Air Force will form a committee to look into the cause of the accident.

The accident follows two other fatal air crashes in March, which left three dead.

F-5 fighters are South Korea's domestic-manufactured aircrafts in 1980's. The country now operates about 180 F-5 fighters.

A total of 14 Air Force jets have crashed since 2004.