Jess Roskelley, David Lama and Hansjörg Auer had been attempting a difficult climb in Banff National Park. They were reported overdue on Wednesday, according to the park.

Three of the world’s most elite climbers are missing and presumed dead by park officials after an avalanche in Alberta, Canada.

Jess Roskelley, a U.S. citizen, and David Lama and Hansjörg Auer, who are both Austrian, had been attempting to climb the east face of Howse Peak in Banff National Park. They were reported overdue on Wednesday, according to the park.

“Based on an assessment of the scene, all three members of the party are presumed to be deceased,” the park said.

A statement from Parks Canada said that responders “observed signs of multiple avalanches and debris containing climbing equipment.”

“Search and recovery efforts are not currently possible due to weather and dangerous avalanche conditions,” it said. The avalanche hazard is expected to continue, Parks Canada said, because of more strong winds and precipitation.

Washington native Roskelley, 36, was the youngest American to summit Mount Everest. He accomplished the feat when he was 20 with his father. John, who is also a well-known climber.

Jess Roskelley has been called “one of America’s boldest alpinists,” Men’s Journal wrote. The…