( CNN ) -- A U.S. team was at work Monday at a Himalayan military outpost in Pakistan , joining the search for as many as 139 people buried in a massive avalanche . The eight-member U.S. group of experts arrived Sunday , the official news agency Associated Press of Pakistan ( APP ) reported . Three experts from Switzerland and six from Germany were on their way to Pakistan on Monday as well , according to the Pakistani military . About 300 Pakistani soldiers and civilians were working at the rescue site , using heavy machinery and helicopters , the military said . APP said around 124 troops and 11 civilians could be trapped . The military said Sunday that as many as 139 people were believed trapped . A blanket of rock and snow covering one square kilometer -- about the size of a large city block -- slid over the base on the Siachen glacier near the Indian border on Saturday morning , burying it under 70 feet of snow . It was the first such disaster at the mountain headquarters in its two decades of existence , the military said . The U.S. Embassy in Islamabad expressed condolences for those who have lost their lives , and offered `` any assistance that Pakistan requires in the aftermath of this tragedy . ''
The U.S. team includes 8 experts . They are also coming from France and Germany . As many as 100 people could be trapped , officials say .