The search for two climbers missing from a mountain in Alaska’s Denali National Park is narrowing after authorities determined that «survival is outside the window of possibility.»

The climbers, Eli Michel, 34, of Columbia City, Indiana, and Nafiun Awal, 32, of Seattle, are believed to have been swept from Moose’s Tooth Mountain by an avalanche of flagstones, the National Park Service reported. said thursday.

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

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

The couple’s empty tent and their skis that they had stowed away after switching to crampons were found, and other equipment was seen along a 3,200-foot drop line, authorities said. Temperatures have been between 5 and 20 degrees at night.

«Search administrators have concluded that survival is outside the window of possibility,» the park service said in a statement.

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