Gangtok, April 4 : At least seven tourists were killed on Tuesday in Sikkim after a massive avalanche hit a section of National Highway 310, an official said. The Border Roads Organisation (BRO) has managed to rescue at least 350 tourists stranded in the affected area after they were stuck due to the avalanche, defence sources said. Defence spokesperson Lt. Col Mahendra Rawat said the avalanche hit the Gangtok-Natu La Jawahar Lal Nehru Marg on National Highway 310. He said that around 30 tourists travelling in 5-6 vehicles on their way to Natu La were buried beneath the snow. Troopers of Trishakti Corps of the Indian Army and BRO personnel under 'Project Swastik' swung into action immediately, and launched an all-out rescue mission. A total of 23 people, including six from a deep valley, have been pulled out alive. They have been shifted to the nearby medical facilities of the Indian Army. "Unfortunately, seven tourists have died. Search and rescue missions are underway by the Army, State Disaster Management team and police," Lt. Col. Rawat said. So far, 350 stranded tourists travelling in 80 vehicles have been rescued after clearing the snow from the road. Rescue operations are currently underway. Further details are awaited. /IANS