An American and a Swiss died while attempting to climb Mount Everest, according to their expedition organizer in Nepal. They are the only deaths on the mountain to date this season.

Swiss climber Abdul Waraich, 41, reached the peak before encountering difficulties, Chhang Dawa of the Seven Summit Treks in Nepal said.

"Abdul successfully reached the summit but began experiencing issues during his descent," Dawa said. "We sent two additional Sherpa with oxygen and food. Unfortunately, the Sherpa couldn't save him."

Puwei Liu, a 55-year-old U.S. national, died at the mountain's highest camp, South Col. He had made it to the Hillary Step - between the South Col and the summit - but had to turn around owing to snow blindness and exhaustion.

He was returned to camp at South Col but died late Wednesday, according to organizers.

No other information was available. Other Climbers have been forced to descend because of the weather.

This season saw the first summits of Everest Friday. On the same day, Nepali climber Kami Rita Sherpa set a record by scaling the mountain for the 25th time.

Hundreds of mountaineers are acclimatizing on Everest's lower slopes - aiming to climb the mountain during favorable weather in coming days.

Last year, both Nepal and China canceled climbing on the 8,849-meter-high (29,032-foot) mountain that divides them. China is allowing only climbers from that country on the north side of the mountain this year.

May is normally the best time to climb Everest. Scores completed the summit this week and more are expected to attempt it as the weather improves.

This year, Nepal permitted foreign climbers to return and the government issued permits to 408 climbers to attempt the peak during the spring climbing season.