An American and a Swiss climber who were part of the Seven Summit Treks team died after reaching the summit of Everest yesterday, as around 150 people have now climbed the mountain this season. They are the first casualties on the world’s highest mountain this year.

U.S. national Puwei Liu, 55, died at the South Col after he reached Hillary Step, located between South Col and the summit, but had to bail because of snow blindness and exhaustion. According to SST leader Chhang Dawa Sherpa, “It consumed more hours, but with the help of extra oxygen and additional Sherpa support, he safely reached the South Col late Wednesday evening before he suddenly passed away.”

Swiss climber, Abdul Waraich, 41, reached the summit before having difficulties, said Chhang Dawa. “Abdul successfully reached the summit but began experiencing issues during his descent,” he said. “We sent two additional Sherpas with oxygen and food. Unfortunately, the Sherpas couldn’t save him.”

No other details were given about the deceased climbers and when their bodies would be brought down. Bad weather has forced climbers to descend to lower altitudes to wait for another weather window, which might not come until next week.

Everest was the last of the Seven Summits for Waraich. Liu was also an experienced climber who summited Makalu in 2017.

Nepal and China both cancelled climbing seasons last year, and China is allowing only Chinese climbers on the north side of the mountain this year. Nepal allowed foreigners to return this year and the government issued permits to 408 climbers. May usually has the best weather for climbing Everest before the monsoon season.