Nine die in worst-ever K2 climbing disaster

At least nine climbers have died on the world's most dangerous mountain after a series of incidents led to chaos on the slopes of K2. Officials say a number of other climbers are missing and that the death toll could rise. In what was described as one of the blackest weekends in mountaineering, six of the climbers were struck by an avalanche while descending from the summit of the mountain, the second highest after Everest. Three more died in separate incidents.

The fatalities came after 22 climbers from eight expeditions reached the summit on Saturday and then began the perilous journey back down the mountain. "They were returning from the summit when an avalanche at the Bottleneck hit them," Ghulam Mohammad, a tour official, told Reuters.

While precise details remain unclear, it seems that a serac – a pinnacle or pillar of ice – gave way. This killed some of the group and destroyed a number of fixed climbing ropes on the steep gully known as the Bottleneck, leaving other climbers stranded. The Bottleneck is located at a height of more than 26,000ft (8,200m). Climbers call it the Death Zone. Fredrik Straeng, a Swedish climber, described the incident to the Swedish news agency TT, saying he believed more than nine climbers died: "I have carried down both living and dead people from the mountain. I panicked when a [climber] fell straight on to my back ... I was terrified that we would all be pulled off the cliff and screamed to him to use his ice axe, but he lost his grip and plummeted off a 300-metre cliff."

The summit of K2, on the border of Pakistan and China, is 800ft lower than Everest, but experts agree K2 is a more challenging climb and statistically it remains one of the deadliest mountains for fatalities. At least 70 climbers have died on the mountain, many at the Bottleneck. Officials said a team of climbers had begun ascending the mountain to take supplies to those still trying to make their way down. Helicopters were being readied to bring down injured climbers and spotter planes are standing by.

Last night there was confusion about the nationality of those climbers still missing. One report said five members of a Dutch team were still missing, while there was also no news about an Irish climber Gerard McDonnell, a French climber Hugues d'Aubarede and a third climber identified only as "Karim".

On Friday, Mr McDonnell had achieved his ambition of becoming the first Irishman to climb K2 after an earlier failed attempt. His friends and family were last night hoping that reports of a lone figure making their way down the mountain was Mr McDonnell. A Korean team lost five members, including two Nepalis.

Among those confirmed dead were three South Koreans, two Nepalese, along with Serbian, Norwegian, Dutch and French climbers. Norwegian media are reporting that Rolf Bae, 33, died in the disaster, while his wife is reportedly trying to make her way down with two other Norwegians. Unconfirmed reports said one Pakistani had died and some foreign and local climbers were unaccounted for.

In August 1995, six people fell or disappeared during a storm on K2, among them a British climber, Alison Hargreaves.

The head of the Italian mountaineering group Ev-K2-CNR, Agostino Da Polenza, told SkyItalia television: "According to the rumours from the ... base camp, there should be nine people dead and four still missing."

Major Farooq Firoz, a spokesman for the Pakistan military which is organising the search missions, said: "We were told that some climbers are still returning to the camps."

A Dutch expedition said on its website that three of its team were descending from Camp Three, at 7,350 metres. Two of them were suffering from frostbite.

The deadliest descent

*K2 is the second highest mountain in the world at 8,611m or 28,251ft.

*It was first conquered by Lino Lacedelli and Achille Compagnoni, part of an Italian expedition, on 31 July 1954.

*In an earlier attempt in 1953, climber Art Gilkey was killed, either in an avalanche or in a deliberate attempt to avoid burdening his companions.

*Those mountaineers who reach the peak have a much greater chance of dying while descending than on other peaks: 27 per cent have perished making their way back down – a rate three times higher than on Everest.

*1986 was known as the 'black summer': 13 out of 27 to try the ascent died. Polish climber Wanda Rutkiewicz became the first woman to reach the top, but Liliane Barrard – who became the second minutes later – and her husband, Maurice, did not complete the descent.

*On 13 August 1995, a storm caused six people to fall or disappear, the previous record for the mountain's deadliest day. Among them was Alison Hargreaves, the first woman to climb Everest without oxygen or sherpas.