Jess Roskelley, David Lama and Hansjorg Auer are believed to be dead after an avalanche in Canada’s Rocky Mountains.

Three renowned professional alpinists are missing and presumed dead after an avalanche in Canada‘s Rocky Mountains, Parks Canada has said.

Climbing media named the men as American Jess Roskelley, 36, and Austrians David Lama, 28, and Hansjorg Auer, 35, saying they were killed after attempting to climb a challenging route on Howse Peak in Banff National Park.

Parks Canada described the area as “a remote and an exceptionally difficult objective .. [that] required advanced alpine mountaineering skills.”

Canadian authorities did not release the names of the three men but said they were one American and two Europeans and described them as highly experienced professional mountain athletes.

David Lama, Jess Roskelly, and Hansjoerg Auer were among the best—each an incredible mountaineer, partner, & friend who enriched our community immeasurably. They will be deeply missed; may we continue to find inspiration in their ideals & accomplishments. https://t.co/SlA4A88poL — American Alpine Club (@americanalpine) April 18, 2019

Roskelley was best-known for climbing Mount Everest at age 20 in 2003, making him the youngest person at the time to have climbed the world’s highest mountain.

Lama and Auer were also world-class mountaineers who had climbed some of the toughest routes around the globe.

Parks Canada said in a statement the party was attempting the east face of Howse Peak. The three men probably started their ascent on Tuesday, Stephen Holeczi, Parks Canada visitor safety specialist said.

They were reported overdue on Wednesday.

“Parks Canada visitor safety specialists immediately responded by air and observed signs of multiple avalanches and debris containing climbing equipment,” the statement said.

Holeczi also said there was “strong evidence” that all three climbers were deceased.

There currently is no timeline for when search and recovery efforts can begin, Holeczi said, because of bad weather and the risk of avalanche in the area.

Roskelley’s father, John Roskelley, was himself a world-renowned climber who had many notable ascents in Nepal and Pakistan, mostly in the 1970s; he had joined his son on the successful Everest expedition in 2003.

John Roskelley told The Spokesman-Review the route his son and the other climbers were attempting was first done in 2000.

“It’s just one of those routes where you have to have the right conditions or it turns into a nightmare. This is one of those trips where it turned into a nightmare.”