A British climber died on the slopes of Mount Everest on Saturday, bringing the death toll this season on the world’s highest peak to 10, officials said.

A 41-year-old British climber, Robin Haynes Fisher, reached Everest’s peak at 8:30 a.m. local time on Sunday morning and collapsed and died shortly after, at about 150 meters below the summit, according to Murari Sharma, Managing Director at Everest Pariwar Treks. Despite efforts to wake him and to give him oxygen and water, the climber remained unresponsive and guides radioed their base camp to confirm he had died just 45 minutes after Mr. Fisher had stood atop the mountain.

Reports said one of his Sherpa guides had also complained of feeling ill. He was rescued and brought to a camp at lower altitude.

The deaths come amid reports of massive crowding on the mountains, especially around the Hillary Step, where climbers have to go single-file. Nepal is facing scrutiny for issuing a record 381 permits, at $11,000 each, for this year spring’s season.

“I have climbed Everest so many times, but this spring’s traffic jam was the worst I have ever seen,” said Tapering Jangbu Sherpa.

Haynes Fisher is one of the 10 climbers to have died over the past few weeks of the spring climbing season as conditions on the highest mountain turned lethal. Other deaths from this week include four climbers from India, one from Utah, a Nepalese guide, one Austrian and one Irishman.

Officials suspects another Irishman has also died after falling on the mountain last week. The search for his body had been called off.