**Two South Korean fighter jets have crashed into a mountain during a training mission in the east of the country, defence officials have said.**Three pilots were onboard the F-5 jets when they hit Mount Hwangbyeong, near Gangneung, about 237km (711 miles) east of Seoul, said the Yonhap news agency.
Climbers reported seeing aircraft debris on the mountain, said Yonhap.
The cause of the incident is not yet known, but officials said poor visibility could have been to blame.
A search and rescue operation using two military helicopters has been launched.
The jets disappeared from radar shortly after taking off from an airbase in Gangneung.
“We are currently searching for the missing pilots near the area,” an Air Force spokesman told Yonhap.
“There is a high possibility that the aircraft crashed due to bad visibility from the foggy weather. We will further investigate the causes.”
One witness reported “a thundering noise and acrid smoke near the mountain’s summit”.
Yoon Heung-joon said he saw what he believed to be the wreckage of the planes on the mountainside.
Yonhap said if confirmed, the crash would be the seventh involving South Korea’s ageing F5 fleet since 2000.