Three South Korean fighter pilots have died after their jets crashed into a mountain during a training mission. Defence officials in Seoul said the F-5 jets were believed to have hit Mount Hwangbyeong, near Gangneung, about 237 kilometres east of Seoul. <br/><br/>The jets disappeared from radar shortly after taking off from an airbase in Gangneung. A search and rescue operation was launched but an official later said all three pilots had died. Rescue teams found debris, clothing and body parts on the mountain.<br/> <br/>The cause of the incident is not yet known, but officials said poor visibility could have been to blame.<br/>