One of the deadliest avalanches ever to occur on Mount Everest killed 13 and seriously wounded 3 Sherpa guides on Friday, The Guardian reports.

Several others are missing and rescue teams are combing the debris field to find them, says Tilak Ram Pandey, an official at Nepal's Tourism Ministry. "There were around 15 climbers from six different expeditions including Alpine Ascent and Summit Nepal, when the avalanche swept them away," he said.

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Nearly 100 guides and climbers have been trapped above the avalanche site, The New Indian Express reports.

The avalanche hit a group of about 50 people, all of them Sherpas, at an altitude higher than 20,000 feet just above base camp in the Khumbu Ice Fall, in an area known as the "popcorn field." The guides were preparing ropes that will lead the hundreds of climbers who are expected to try and conquer Mt. Everest during the spring climbing season.

The Sherpa guides are paid to safely accompany climbers who are not from Nepal.

Until now, the single deadliest accident on Mount Everest happened in May 1996, when 8 people were caught in a blizzard and died while trying to reach the summit of the mountain. That incident was chronicled in Jon Krakauer's bestselling book "Into Thin Air."