Two Americans, an Irishman, and a Swiss climber have been identified by Denali National Park officials as the quartet involved in an accident near the roof of Mount McKinley that wound up killing one of the four.

The accident, which occurred late Wednesday or early Thursday morning, led to the death of 38-year-old Beat Niederer of St. Gallen, Switzerland, park officials said Saturday.

The four, roped together, were heading down from the summit when they slipped and fell. Jeremiah O’Sullivan, 40, of Ballinhassig, Ireland, suffered a broken leg in the fall, according to park officials. The guide, Dave Staeheli, 56, of Wasilla, Alaska, directed the other two climbers in the group -- Lawrence Cutler, 45, of Croton-on-Hudson, New York and Mr. Niederer -- to head down to the mountain's high camp, at 17,200 feet, while he stabilized Mr. O'Sullivan in a bivy sack at an elevation of 19,500 feet, a park release said.

After securing Mr. O'Sullivan, Mr. Staeheli, who guides for Mountain Trip, headed down to the high camp. When he arrived, another team of climbers was able to call for help via satellite phone. However, neither Mr. Cutler nor Mr. Niederer had arrived at the camp, a park accounting said.

Search teams from both the park and the Alaska Air National Guard subsequently were able to rescue Mr. O'Sullivan -- who also suffered from severe frostbite to his hands, legs and face -- Thursday evening, and recover the body of Mr. Niederer, which was found at about 18,000 feet, park officials said. The climber's cause of death was not immediately determined.

On Friday it was decided that neither Mr. Staeheli, who suffered from frostbite to his hands and feet and a broken rib sustained in another fall, and Mr. Cutler, who had frostbite to his hands and feet, couldn't make it to the bottom of McKinley on their own and were airlifted out, park officials said.

Both men were individually shorthauled from the 17,200-foot camp to the 14,200-foot camp by NPS ranger John Loomis and B3 helicopter pilot Andy Hermansky, the park said.  From there, the helicopter flew them down to the Kahiltna Basecamp for a fixed wing flight back to Talkeetna.

An additional client who had turned back along with a guide earlier Wednesday during the  summit bid due to frostbite on his fingers was evacuated from the 14,200-foot camp by the Park Service on Thursday afternoon.  He has been identified by park officials as Tony Diskin, 33, of Westmeath, Ireland.

As of the morning of May 14, there were 282 climbers attempting Mt. McKinley.  Eight summits have been recorded thus far.  A total of 1,029 climbers are registered to climb during the 2011 season.