A helicopter plucked two frostbitten Dutch climbers from K2 after an avalanche and exposure left at least 11 people presumed dead on the world's second-highest mountain. An Italian who was also stranded made his way down the slope with a rescue team after telling a colleague, "I am surely not going to give up now."

Italian Marco Confortola, descended to 20,340 feet but bad weather forced officials to abort a helicopter rescue Monday, said Shahzad Qaiser, a top official at the tourism ministry. He was climbing down on foot, despite frostbite, assisted by a support team from a base camp.

Another attempt was planned for Tuesday, Qaiser said.

K2, which lies near Pakistan's northern border with China, is regarded by mountaineers as more challenging to conquer than Mount Everest, the world's highest peak. K2 is steeper, rockier and more prone to sudden, severe weather.

Agostino Da Polenza of Everest-K2-CNR, an Italy-based high-altitude scientific research group, also spoke to Confortola on Monday.

"I never gave up in my life, I am surely not going to give up now," Da Polenza quoted the climber as saying on his group's Web site.

One of the men rescued Monday, Wilco Van Rooijen, blamed mistakes in preparation for the final ascent — not just the avalanche — for one of mountaineering's worst disasters.

"Everything was going well to Camp Four, and on summit attempt everything went wrong," Van Rooijen told The Associated Press by phone from a military hospital, where he was being treated for frostbitten toes.

Van Rooijen said several expeditions waited through July for good weather to scale K2 and decided to go for the summit when winds dropped on Friday. In all, about two dozen climbers made the ascent, officials said.

But Van Rooijen said advance climbers laid ropes in some of the wrong places on the 28,250-foot peak, including in a treacherous gully known as as "The Bottleneck."

"We were astonished. We had to move it. That took of course, many, many hours. Some turned back because they did not trust it anymore," said Van Rooijen, 40.

He said those who went on reached the summit just before nightfall. As the fastest climbers descended in darkness across The Bottleneck, about 1,148 feet below the summit, a huge serac, or column of ice, fell. Rooijen said a Norwegian climber and two Nepalese sherpas were swept away. His own team was split up in the darkness.

The Ministry of Tourism released a list of 11 climbers believed dead: three South Koreans, two Nepalis, two Pakistanis and mountaineers from France, Ireland, Serbia and Norway.

At least two fell on their way up the mountain, before the avalanche.

About 280 people have summited K2 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.