At least nine climbers were feared dead on K-2, the world's second-highest mountain, after an avalanche cut ropes used to cross a treacherous wall of ice, officials and other climbers said on Sunday.
Several other mountaineers were missing, prompting a desperate rescue effort on the peak in northern Pakistan, which is regarded as more dangerous to climb than Mount Everest.
A total of 22 people, mostly foreigners, in eight different groups scaled K-2's summit on Friday, said Nazir Sabir of the Alpine Club of Pakistan.
As they made their way down, an avalanche carried away ropes fixed 1,148 feet (350 meters) below the peak, sweeping some climbers to their deaths and stranding others at a height where they would likely succumb to exposure, Sabir said.
Accounts varied on the number of dead and how they died. Sabir said nine people died in the avalanche. Included in that number, were two rescuers _ a Nepalese sherpa and a Pakistani porter _ who survivors said fell to their death.
Mohammed Akram, vice president of the Adventure Foundation of Pakistan, a nonprofit organization, said one rescue team dispatched on Sunday had reached a Dutchman and an Italian suffering from frostbite and were helping them down toward a camp at an altitude of 21,325 feet (6,500 meters).
He said helicopter crews spotted survivors, but could not pluck them to safety because the air is too thin for them to operate so high.
The fixed rope lines were strung across a point on the mountain known as "The Bottleneck." Chris Warner, an American who climbed K-2 last year, said it was the deadliest place on the mountain, the fall from there down the south face is some 9,000 feet (2,740 meters).
"You can see how for people who were exhausted, it would have been nearly impossible for them to descend without the ropes," said Warner.
He said hope was fading for anyone still alive and separated from their group. "Once their hands and feet are frozen, they really are unable to move on their own power, and it takes other people to carry them down," he said.
At 28,250 feet (8,610 meters), K-2 stands about 785 feet (240 meters) below Mount Everest, but is a "phenomenally dangerous mountain," said Alan Arnett, who climbed a nearby peak with at least one of the missing climbers.
Compared with Everest, "it's more technical, it's steeper, the weather is more intense," he said.
The toll from the avalanche was the highest from a single incident on K-2 since at least 1995, when seven climbers died after being caught in a fierce storm.
About 280 people have summited K-2 since 1954, when it was first conquered by Italians Achille Compagnoni and Lino Lacedell. Dozens of deaths have been recorded since 1939, most of them occurring during the descent.