( CNN ) -- Eleven climbers died on Pakistan 's K2 mountain after an ice avalanche knocked down a fixed rope climbers were using to reach the summit , a mountaineer at their base camp said Sunday . Pakistan 's K2 is the second highest peak in the world . Among the dead was a sherpa who had gone up K2 -- the world 's second tallest mountain -- to help in rescue efforts , said mountaineer Fredrik Strang , who also assisted in the rescue attempts . The deaths happened after 17 climbers , in different expeditions from around the world , had come together to make it to K2 's peak on Friday , said Pat Falvey , a climber in Ireland who was in touch with some of the 17 . As the 17 were descending early Saturday , a `` moving river of ice broke loose ... like an iceberg breaking loose from a glacier , '' knocking down the fixed rope the group had been using to move from higher reaches to a camp at a lower altitude , Falvey said . The rope 's collapse caused three climbers to fall to their deaths , said Falvey , who was posting online updates for one of the expeditions . iReport.com : Are you a mountain climber ? Ever attempt K2 ? Two climbers decided to go on and managed to return to base camp , but the rest decided to wait and hope rescuers could reach them , Falvey said . The avalanche had created `` icy , dangerous conditions '' on the slope , Falvey said . As time went on and rescuers did n't come , the remaining climbers decided to continue their descent , but some of them fell to their deaths in the mountain 's `` bottleneck '' area , Falvey said . The rest eventually were helped down by rescuers , Falvey and Strang said . Falvey and Strang said the survivors told them what had happened but were not immediately in condition to speak publicly . See a map of K2 mountain » . Among the killed climbers were Dutch , Irish , Italian , French , Norwegian , Korean , and Nepalese citizens , Falvey said . One of the killed was Irish climber Gerard McDonnell , Falvey said . The bodies of the 11 may never be recovered , but rescuers and the mountaineers who made it down are certain the 11 are dead , Strang said . The site of the accidents , about 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 , Falvey said . Strang said Sunday the death toll was not expected to rise , because no one else was believed to be missing . Strang said the deaths could have been avoided . Too many people were climbing together `` at a very slow speed '' and should have begun their descent sooner , he said . `` Coming down at dawn , in the dark , with little oxygen is very , very dangerous , '' he said . Though K2 is the world 's second-highest mountain , many climbers consider it more technically challenging than Mount Everest , the world 's highest peak . Statistics compiled by AdventureStats.com suggest this was the deadliest incident at K2 . The site says 66 people -- not counting those in the latest incident -- have died on the mountain since 1939 . A chart compiled by viewfinderpanoramas.org lists 284 climbers as having ever reached the summit of K2 .
Mountaineer says 11 dead , including sherpa who tried to rescue climbers . 17 climbers had made summit at K2 -- world 's second-highest mountain . - May 6 :