The last survivor of the deadliest mountaineering disaster ever to hit the world's second-highest peak was rescued by helicopter Wednesday, nearly five days after the tragedy, a Pakistani army spokesman said.

Italian Marco Confortola, three members of his support team, and a group of South Koreans were taken from K2's base camp to a nearby town, spokesman Maj. Farooq Feroz said.

As many as 30 mountaineers began their ascent of K2 on Friday. An avalanche swept some climbers away and left others stranded in frigid conditions just below the 28,250-foot summit. In all, 11 people died: three South Koreans, two Nepalis, two Pakistanis and mountaineers from France, Ireland, Serbia and Norway.

Fatal accidents are common on the treacherous peaks that attract top mountaineers to Pakistan each summer, but this is the deadliest single incident in memory, surpassing the seven climbers killed on K2 during a fierce storm in 1995.

K2, which straddles Pakistan and China in the Karakoram range, is regarded by mountaineers as far more challenging than Mount Everest, the world's highest peak. The mesmerizing giant pyramid of K2's knife-edged ridges and icy slopes are steeper and prone to both avalanches and sudden and severe storms.

Confortola, 37, was the last survivor to reach safety. He limped into base camp with frostbitten feet Tuesday, but thick clouds forced him to stay an extra night. Authorities took him to a military hospital.

Feroz said the 12 South Koreans already at the base camp requested to be airlifted down because they were having difficulty hiking.

"I am happy to be alive," Confortola told Everest-K2-CNR, an Italy-based high-altitude scientific research group, during a phone call from the camp at 17,000 feet.

The group's spokeswoman, Francesca Steffanoni, said the mountaineer was examined by an American doctor and reported to be in good condition, despite his toes blackened by frostbite.

"I am fine, luckily I'm made of stern stuff," Confortola said, according to a transcript of the conversation. "The only problem is that my feet hurt. I spent seven days on that mountain. It was hard. It was terrible."

Confortola told Italy's SKY TG 24 TV that he would return to Italy "as soon as possible" to see a doctor he trusted to treat his feet and lower limbs.

The Italian also echoed criticism of the expedition voiced by a Dutch climber rescued Monday. Confortola said the expedition was undermined by inexperience and low-quality equipment, including ropes and spikes that easily broke.

He told Everest-K2-CNR that he felt helpless when he and others made a futile attempt to rescue the three Koreans dangling from a rope. He said he was too weak and had to give up.

"I couldn't take it anymore, I descended" alone, Confortola said. "The descent was devastating, especially the last part."

His plight has been front-page news for days in Italy with constant updates on his progress broadcast on TV. He was escorted part of the way down to base camp by three others, including an American climber.

Government officials in Islamabad have promised to investigate the tragedy.

"We cannot sit as a spectator to this," said Shahzad Qaiser, a top official at the Ministry of Tourism, which oversees tour companies that provide services to mountaineering expeditions. "This accident is a very sad and disastrous event in our mountaineering history."

Qaiser said the Alpine Club of Pakistan and ministry officials would talk with survivors, investigate how so many climbers died and probe any complaints. He said any Pakistani tour operators found negligent could face legal action and lose their licenses.

One Dutch survivor, Wilco Van Rooijen, who was rescued Monday, blamed mistakes in preparation — not just the avalanche — for the loss of life.

Van Rooijen told The Associated Press on Monday that advance climbers laid ropes in some of the wrong places, including in a treacherous gully known as "The Bottleneck," about 1,150 feet below the summit, where the ice fall later took place.

That caused hours of delays, so climbers reached the summit just before nightfall, while others turned back. Ice overhanging the route fell as the fastest mountaineers were descending some of the iciest and most difficult sections just below the summit.

Qaiser said he had yet to receive a formal complaint against any tour operator, and added the responsibility for placing ropes on a mountain lay with the mountaineers themselves. Not all climbers who have been up K2 believe those sections require fixed ropes.

About 280 people have reached K2's summit since 1954, when it was first done by Italians Achille Compagnoni and Lino Lacedell. Dozens of deaths have been recorded since 1939, most of them occurring during the descent.