Kathmandu, 19 January :The whereabouts of seven trekkers including four Korean citizens and three Nepali guides who had gone missing in an avalanche on Friday that swept the Annapurna circuit trekking route, are still unknown. According to police, they rescued other five avalanche-trapped trekkers and airlifted them to safer places.  More than 100 trekkers  that were left stranded  were rescued from the Machhapurchhe Base Camp earlier .  Three choppers were used in rescue operation. The avalanche occurred at an altitude of 10,600 feet along the trekking route. People's News Monitoring Service