Three professional climbers are presumed dead after an avalanche in the Canadian Rockies, authorities say.
The three mountaineers were attempting to scale Howse Peak and failed to check in on schedule.
National park staff flew over the area where they were climbing and saw evidence of "avalanches and debris containing climbing equipment".
Recovery efforts are on hold because of dangerous conditions and additional avalanches at the scene.
Those efforts are likely to be further hampered by bad weather in the coming days.
Outdoor clothing company The North Face has identified the men as David Lama and Hansjoerg Auer from Austria, and Jess Roskelley, from the US.
The three were sponsored by the firm which said in a statement it was doing everything it could to support their families, friends and the climbing community.
The climbers went missing when they were attempting to scale the east side of Howse Peak, which Parks Canada described as a "remote and an exceptionally difficult objective, with mixed rock and ice routes requiring advanced alpine mountaineering skills".
The route taken by the climbers was rarely traversed, safety specialist Steve Holeczi said during a press conference.
Mr Holeczi, who was among those who flew over the avalanche site, estimated the avalanche to be strong enough to destroy a small building.
Howse Peak, with a 3,295 metre (10,800 foot) elevation, is in the Canadian province of Alberta, in Banff National Park.
Who are the men?
Mr Roskelley, 36, from Spokane, Washington state, scaled Mount Everest at age 20.
The son of a famous mountaineer, he was the youngest American to reach the summit of the world's highest peak in 2003.
Mr Lama, 28, is also from a climbing family - his father was a mountain guide from Nepal - and his talent was recognised at an early age.
He won numerous climbing competitions as a teenager.
In 2014, a film was released that documented his attempt to become the first person to free-climb the Compressor Route on Patagonia's Cerro Torre mountain.
Mr Auer, 35, grew up on a family farm in Austria near the Dolomite mountain range.
Among his most recognised climbing achievements are the southwest-face ascent of Pakistan's Kunyang Chhish East in the Karakorum Mountains and the first ascent of the south face on Nilgiri South in Nepal.
Fellow climbers and many in the global climbing community expressed sadness at the reports.
So sad to hear the accident of Hansjörg Auer, David Lama and Jess Roskelle. 3 of the most cutting edge alpinist of the last years 🙏 https://t.co/oXhebg244Y— kilian jornet (@kilianj) April 18, 2019