TWO people were killed and two students injured yesterday when a hiking trip on Tai Mo Shan, Hong Kong's highest peak, turned to tragedy. Leung Ka-lok, 33, and Ng How-kuen, 31, were certified dead on arrival at the Jockey Club Clinic in Tai Po after a landslip swept them over a cliff near Ng Tung Tsai. Another six people in their group were stranded, but not hurt. The injured couple were first spotted 20 metres down the cliff face by students Kwok Chun-chiu, 17, and Chong Kan-chou, 20, who were out taking pictures. But when they tried to reach Leung and Ng, they also slipped and were hurt in the fall. According to rescue teams, Kwok was unconscious but Chong managed to walk for 90 minutes to raise the alarm. He then led a rescue team back to the scene where they spotted the other hikers. Bad light meant helicopters could not be used in the rescue, so firemen and Civil Aid Services officers used ropes to lower themselves down to the casualties. The pair were pulled up on stretchers and then carried for another 90 minutes to ambulances. Kwok and Chong were in satisfactory condition at the Prince of Wales Hospital early today.