(CNN) -- Two Dutch adventurers who survived a deadly ice avalanche that killed 11 other climbers on K2, the world's second highest mountain, were airlifted to a Pakistani hospital Monday, the team's spokesman told CNN.
Twenty-two climbers, mostly foreigners, reached K-2's summit Friday before a deadly avalanche struck.
An Italian climber, Marco Confortola, also survived the ordeal and will be airlifted once he reached a lower altitude, the country's Ministry of Tourism secretary said.
"So the search is on and I am very hopeful that he (Confortola) will be able to descend ... where he could be rescued," Shahzad Qaiser said.
The two Dutch survivors, Norit expedition leader Wilco Van Rooijen and Cas Van de Gevel, had been "stuck up high on the mountain" since the avalanche on Friday, team spokesman Michel Schuurman said.
The two men, who arrived at base camp on Saturday, were flown to a military hospital in Skardu, Pakistan on Monday, Qaiser added.
Among the 11 casualties was a local sherpa who had gone up to assist in rescue efforts, mountaineers working with the climbers involved said.
According to a Web log offering frequent updates on the rescue effort, Van Rooijen -- an accomplished climber who has scaled Mt. Everest without supplementary oxygen -- may be suffering from frostbite "and is not out of danger yet." Watch how the climbers were rescued »
"Still, this survival is bound to go down as one of the greatest mountaineering tales in K2's history," K2climb.net said.
The avalanche struck down the safety ropes that the climbers planned to use to descend the mountain, Schuurman said.
"They had to descend without any safety lines and in that descent we know that some climbers have slipped down and their whereabouts are unknown," Schuurman said.
He said the rescue team may ask Pakistani authorities "to send an airplane that could make a circle around the mountain to see if they can locate anyone."
According to Fredrik Strang, who assisted in the rescue efforts, the avalanche killed 11 climbers from different expeditions who had come together to make it to the peak of K2, which many climbers consider even more technically challenging than world's tallest peak, Mt. Everest.
Strang said Sunday the death toll was not expected to rise, because it was not believed anyone else was missing.
The site of the accident, about 8 kilometers (5 miles) up the mountain, is what climbers call the "Dead Zone," because the body would never recover if stuck in such freezing conditions with so little oxygen, said Pat Falvey, a climber in Ireland who is in touch with the climbers and posting updates online for one of the climbing expeditions. Map of the area »
The climbers were Dutch, Irish, Italian, French, Norwegian, Korean, and Nepalese citizens, Falvey said.
While the climbers and rescuers who made it down safely were not immediately in condition to speak publicly, they told Strang and Falvey what had happened.
On Friday, 17 climbers reached the summit together -- one of the largest groups ever to reach the summit simultaneously -- said Falvey. As they were descending, a "moving river of ice broke loose... like an iceberg breaking loose from a glacier," and it knocked down the fixed rope that the group had been using to move safely from the higher reaches to a camp at a lower altitude, he said.
The rope's collapse knocked down three climbers, sweeping them away in an avalanche of ice and killing them, he said.
"Not only did it wipe away the fixed ropes, but it brought the whole slope into icy dangerous conditions." iReport.com: Ever tried to climb Pakistan's K2?
Two climbers managed to make it to base camp, but many of those stranded decided the best course of action was to wait and hope rescuers could put up ropes and make it up, Falvey said.
As time went on and rescuers didn't come, the remaining climbers decided their only chance at survival was to go into the treacherous, icy conditions of the mountain's bottleneck and try to make it through. But as they did, some climbers fell to their deaths.
A few managed to survive, with the help of rescuers, Falvey and Strang told CNN.
It is the deadliest incident on K2 since 1986 when 13 of 27 climbers died after summiting the peak, according to Outside Magazine.