Three Mountain Climbers Missing After an Avalanche in Canada

OTTAWA — Three professional mountain climbers were missing and presumed dead on Thursday after an avalanche in Banff National Park in the western province of Alberta.

The three were identified as Jess Roskelley, an accomplished American mountaineer, and David Lama and Hansjörg Auer, both Austrian, by the North Face clothing company, their sponsor.

When the men failed to return from their climb as scheduled on Wednesday, Parks Canada, the government agency responsible for the park, said that it immediately sent aircraft to search for them. The aerial survey found, the agency said, “signs of multiple avalanches and debris containing climbing equipment” in the area where the three had been climbing.

“They are missing and local search and rescue has assumed the worst,” the North Face said in an email. “We are waiting to learn additional information as the search mission continues.”

Mr. Roskelley is the son of John Roskelley, a well-known mountaineer and author. In 2003, when the younger Roskelley was 20, father and son climbed Mount Everest. The son was believed to be the youngest American to have done so at that time.

A biography of Mr. Lama on the North Face website says that he is the son of a Nepali mountain guide and an Austrian nurse. He began climbing at the age of 5 and was widely recognized for his skill when he was a teenager.

Mr. Auer, who was born in 1984, was a mathematics and sports teacher at a secondary school until 2009 when he became a professional climber. In 2016, he received the Paul Preuss Prize, an award for outstanding mountaineers who climb without the help of ropes or other aids.

The parks service said that recovery efforts had been postponed because of “additional avalanches and dangerous conditions at the scene.” Precipitation and high winds, it added, were increasing avalanche risk.

The three men were climbing the east face of Howse Peak, according to the parks service, which is 10,810 feet tall. Stephen Holeczi, a visitor safety specialist for Parks Canada, said at a news conference in Lake Louise, Alberta, that the site was very remote and a “highly technical, alpine route. It’s not a regular route.”

Mr. Holeczi said that because the peak was outside the park’s regular avalanche monitoring zone, weather conditions at the time are unknown. He added, however, that the warming sun of April generally increases the risk of avalanche.

Brandon Pullan, the editor in chief of Gripped, a Canadian climbing magazine, who lives on the edge of the park in Canmore, Alberta, said the three climbers appeared in the area about two weeks ago. The route they were attempting, known as M16, has only been climbed successfully once, 20 years ago, he said.