At least 12 Sherpa guides have been killed after an avalanche swept down the slopes of Mount Everest, Sky News reported. The avalanche hit the area just below Camp 2 at 6,400 metres (21,000ft). Helicopters and rescuers on foot were sent to the scene on the most popular route to the summit and pulled 12 bodies from the snow and ice. Three others were believed to still be missing. Two Sherpas who were injured were taken by helicopter to hospitals in the capital, Katmandu. Ang Tshering, of the Nepal Mountaineering Association, said the area where the avalanche occurred is known as the "popcorn field". The guides had gone out in the early morning to lay ropes for other climbers Hundreds of climbers and guides have gathered at the base camp ahead of their attempt to scale the 8,850 metre (29,035ft) mountain. They have been setting up camps ahead of the peak climbing season at the start of May when the weather is more favourable. Nepal has announced several steps this year to manage the fow of climbers, minimise congestion and speed up rescue operations. Preparations include sending officials and security personnel to the base camp at 5,300m (17,380ft), where they will stay until the end of the climbing season in May. More than 4,000 climbers have scaled the summit since 1953, when it was first conquered by Edmund Hillary and Sherpa Tenzing Norgay. More than 300 people are believed to have died tackling the peak during that time