Climbers missing in Denali National Park are believed dead

The search for two climbers missing off a mountain in Alaska’s Denali National Park is being scaled back after officials determined “survival is outside the window of possibility."

The climbers, Eli Michel, 34, of Columbia City, Indiana, and Nafiun Awal, of 32, of Seattle, are believed to have been swept off Moose’s Tooth mountain by a slab avalanche, the National Park Service said Thursday.

They were last heard from May 5 and reported missing Sunday, it said.

Moose's Tooth is a 10,300-foot-tall mountain in the Ruth Gorge area of the park.

The pair's empty tent and their skis they had cached after switching to crampons were found, and other equipment was spotted along a 3,200-foot fall line, officials said. Temperatures have been between 5 and 20 degrees at night.

"Search managers have concluded that survival is outside the window of possibility," the park service said in a statement.

Denali National Park, which covers 6 million acres, is famous for Denali, a 20,310-foot-tall mountain that is the tallest peak in North America.

This article was originally published on NBCNews.com