KATHMANDU: At least 12 Nepalese Sherpa guides were killed and seven others missing in an avalanche that struck Mount Everest on Friday morning, making it the single deadliest mountaineering accident on the world’s highest peak.

A group of about 50 climbers, mostly Sherpas were moving from Camp I to Camp II when a serac fell off the mountain burying them under the snow at an altitude of about 5,900 metres at about 6:30 am. The Sherpas were going up the mountain to fix ropes and set camps higher up the mountain for their fee-paying clients. ​

“The search for the missing will continue Saturday morning,” said Dipendra Poudel, a mountaineering official.

Another six were injured, two of whom have been brought to Kathmandu for medical treatment. Some foreign climbers were in the group going up the mountain to get acclimatised but they were not among the fatalities.

The single deadliest day before this Friday was May 11 1996 when 11 persons, eight on the Nepal side of the mountain and three on the China side in the north were killed in a snow storm at 8,000 metres, an incident made famous in the Jon Krakauer book Into Thin Air.

According to Poudel, 334 foreign climbers have been given permission to climb the 8,848 metre world’s highest peak in the spring season that lasts till end of May, which is the busiest climb season. About another 400 Sherpa guides accompany these mountaineers. Ethnic Sherpas act as guides for foreign mountaineers.