U.S. National Park Service officials say five people were traveling as one rope team early Thursday morning as part of a Miyagi Workers Alpine Federation expedition on the Alaska mountain.

Park Service spokeswoman Maureen McLaughlin said Hitoshi Ogi, 69, survived after falling 60 feet into a crevasse. He was able to climb out.

The other four tumbled into the avalanche debris and haven’t been seen since. The climbers are presumed dead by either snow burial or injuries suffered in falls

Snowfall and wind have impeded a search for the missing climbers.

Hitoshi spoke to Park Service employees after the event. He said the climbers were descending the mountain together when the avalanche began, McLaughlin said. They sped up, trying to get down the mountain faster, but the rope connecting them broke when the avalanche struck.

Hitoshi was the lowest person on the rope team. He looked for the other four but couldn’t find them.

“He wasn’t sure of all the events,” McLaughlin said, adding that Hitoshi spoke through a translator and was exhausted.

The four missing climbers include 64-year-old Yoshiaki Kato, 50-year-old Masako Suda, 56-year-old Michiko Suzuki, and 63-year-old Tamao Suzuki.

There was new snow on the route, but the weather on Thursday was calm, McLaughlin said.

“Where the avalanche occurred, the vast majority (of the new snow) was not on the main route,” McLaughlin said. “A small sliver of it was, and that’s what took them.”

McLaughlin called the avalanche, “an unlucky, random event.”

“Avalanches do occur in this vicinity, but it’s not common, she said.

The climbers were attempting the busiest route, West Buttress, during the height of mountaineering season. Climbers attempted the route on 92 percent of attempts on Mount McKinley in 2011.

The Park Service said in a news release that nearly 400 people were on the Alaska mountain on Saturday.

Mount McKinley, also known as Denali, is America’s tallest peak. While not a particularly tall peak by global standards, its latitude makes for far thinner air than is found in mountains closer to the equator. That, combined with the weather and temperatures, makes it a particularly dangerous climb.

Four people died on the mountain in 2009 and again in 2010. At least five people died in 2011 on Mount McKinley.

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