A rock slide killed one climber and injured two others as they were descending Mount McKinley's West Buttress route.
The three were attached by rope at 13,000 feet approaching Windy Corner on Sunday night when boulders "the size of trucks" fell on them, said Colby Coombs, co-director of the Alaska Mountaineering School, which led the expedition. A fourth person on the rope, a guide, was not injured.
Clint West, 47, died of multiple injuries shortly after the rock slide. West was an experienced climber and an American citizen who lived in Oxfordshire, England, with his wife and three daughters, Coombs said.
Mark Morford, 47, fractured his right leg and broke his wrist. Morford, who lives in Portland, Ore., underwent surgery on Monday at Providence Alaska Medical Center in Anchorage, Coombs said.
Gerd Islei, a 56-year-old German citizen who also lives in Oxfordshire, suffered three broken ribs, a collapsed lung and a ruptured disc in his lower back.
Morford and Islei's injuries are not life-threatening, Coombs said.
The rest of the 12-member expedition were at Mount McKinley's base camp on Monday, waiting for weather conditions to clear so they could fly to Anchorage.
National Park Service officials said the spontaneous rock slide had falling boulders from 2 feet to 10 feet in diameter. National Park Service officials called it highly unusual for a rock slide of that size to occur on the West Buttress route, and said they were not sure what caused it.
"If there is any additional hazard at this point, we don't know," said Denali National Park spokeswoman Kris Fister.
There have been no other known fatalities on the 20,320-foot elevation Mount McKinley due to rock fall, Fister said.
On Monday, there were between 280 and 300 climbers on Mount McKinley. Many had heard about the death and were taking precautions, Fister said.
Alaska Mountaineering School has four other expeditions on Mount McKinley above the point of the accident, Coombs said.
"I think there is a hyper-concern right now for that location. Without seeing where the rocks came from, I think it's hard to tell if there are other unstable slopes up there," he said.
Rescuers from a camp at 14,200 feet descended to the expedition at about 11 p.m. on Sunday, an hour and a half after the accident. West had already died, according to the Park Service, but the rescuers were able to stabilize Morford and Islei.
A high-altitude helicopter flew the injured climbers off the mountain early Monday morning.