Another three climbers have perished during Himalayan expeditions in Nepal, organisers said Tuesday, casting a shadow over celebrations this week of the first summit of Everest 60 years ago.

A 67-year-old Japanese woman named as Chizuko Kono and 50-year-old Spaniard Juanjo Garra went missing on Friday on Mount Dhaulagiri along with their Nepalese guide and were confirmed dead on Tuesday.

The death toll from this year’s climbing season, the 60th since Tenzing Norgay and Edmund Hillary reached the summit of Mount Everest for the first time, is now at 16.

Garra was marooned high on the mountain after he slipped and broke his ankle, organisers said, but it was not immediately clear what happened to Kono and her guide high on the avalanche-prone peak.

“He couldn’t walk any more, even the next day, but his guide stayed with him to help as much as he could,” Tika Gurung, the expedition organiser told AFP, saying that a helicopter rescue was impossible due to the altitude.

Every May, hundreds of climbers from around the world attempt to scale peaks in the Himalayas when weather conditions are at their best, but the dangers from avalanches, injuries and bad weather remain.

“Although technology has improved mountaineering, there’s only so much it can help in one’s efforts,” Temba Tsheri Sherpa, an Everest veteran who now runs an expedition company told AFP.

Garra was attempting to summit the 8,167-metre peak of Dhaulagiri as part of his quest to top all of the 14 peaks of more than 8,000 metres in the world, eight of which are in Nepal.

To mark the anniversary of the first summit of Everest on Wednesday, Hillary’s son Peter and Norgay’s son Jamling will join Queen Elizabeth II at a diamond jubilee event at the Royal Geographical Society in London.

Celebratory events at Everest include a clean-up campaign at base camp and a high-altitude marathon.

In the capital Kathmandu, a gala featuring record-setting summiteers and top brass from Nepal’s government will be held at the city’s former royal palace.

The celebrations have already been marred by an unprecedented brawl between European climbers and Nepalese guides that erupted on the increasingly crowded mountain earlier this year.

Eight people have died on Mount Everest this season, including a Nepalese Sherpa who had reached the summit ten times and previously ran expeditions to recover dead bodies from the slopes.

Another five climbers died on Kanchenjunga – the world’s third-highest peak – a week ago, according to Nepalese tourism officials.

Above 8,000-metres is known as the “death zone” as the oxygen available is not sufficient to sustain human life.

Dhaulagiri has a high death rate for climbers, according to Himalayan Database, a statistical hub run by Kathmandu-based mountaineering expert Elizabeth Hawley.