At least 12 Nepalese guides preparing routes up Mount Everest for commercial climbers were killed Friday by an avalanche in the deadliest mountaineering accident ever on the world's highest peak, officials said.
The men were among a large party of Sherpas who left Everest base camp before dawn, carrying tents, food and ropes, in an early morning expedition ahead of the main climbing season starting later this month.
Four were still missing, tourism officials said, while one rescuer at the scene said he expected the death toll to rise by at least three after other bodies were spotted.
The avalanche occurred at around 6:45 am (0100 GMT) at an altitude of about 5,800 metres (19,000 feet) -- in an area nicknamed the "popcorn field" due to ice boulders on the route leading into the treacherous Khumbu icefall.
"We have retrieved 12 bodies from the snow," Nepal tourism ministry official Dipendra Paudel told AFP in Kathmandu.
Deteriorating weather conditions forced rescuers to suspend searches for the missing until Saturday morning, Paudel said.
"We do not want to risk another accident," he said.
Aided by rescue helicopters, at least seven people were plucked alive from the mountain and the injured were sent to hospital in the capital.
One survivor said dozens of guides were on the move when the avalanche hit.
"It came out of nowhere, this huge block of ice that fell from above, flying right at us," Dawa Tashi Sherpa told AFP from his hospital bed in Kathmandu.
"I wanted to run but there was no time, we were just trapped," the 22-year-old guide said.
The force of the avalanche fractured Sherpa's ribs, broke his shoulder blades and left him buried in neck-deep snow, before rescuers found him and had him airlifted to the capital.
Kathmandu-based expert Elizabeth Hawley, considered the world's leading authority on Himalayan climbing, said the avalanche was the most deadly single accident in the history of mountaineering on the peak.
The previous worst accident on Everest occurred in 1996 when eight people were killed during a storm while attempting to summit the mountain, first conquered in 1953 by Sir Edmund Hillary and Tenzing Norgay.
The 1996 tragedy was immortalised in the best-selling book "Into Thin Air" by US mountaineering journalist Jon Krakauer and now is the subject of a Hollywood film under production.
"This is the absolutely the worst disaster on Everest, no question," Hawley told AFP.
- Risks for Sherpas -
Every summer, hundreds of climbers from around the world attempt to scale peaks in the Himalayas when weather conditions are ideal.
In the past, some accidents have been blamed on overcrowding or on ill-prepared commercial climbers taking unnecessary risks to reach the summit before returning home.
Friday's accident underscores the huge risks borne by Sherpas, who carry tents, bring food supplies, repair ladders and fix ropes to help foreign climbers who pay tens of thousands of dollars to summit the peak.
A government statement said Dorje Khatri, vice president of a trekking workers' union who had summited Everest at least eight times, was among those killed.
Two years ago, Karsang Namgyal Sherpa, an experienced climber who scaled the peak several times, died on the mountain, apparently due to altitude sickness.
More than 300 people have died on Everest since the first summit in 1953.
Nepal's worst-ever climbing disaster happened in 1995 when an avalanche struck the camp of a Japanese trekking group near Mount Everest, killing 42 people including 13 Japanese.
The impoverished Himalayan country is home to eight of the world's 14 peaks over 8,000 metres.
Nepal's government has issued permits to 734 people, including 400 guides, to climb Everest this summer.
To address worries about overcrowding on the "roof of the world", the government earlier announced plans to double the number of climbing ropes on congested ice walls near the summit of Everest to reduce risks for climbers.
Authorities are also stationing soldiers and police at Everest base camp so climbers can approach officers in case of any trouble following a brawl between commercial climbers and Nepalese guides last year.