An Australian woman and a Dutch man died of altitude sickness and are the first people to be killed on Mount Everest in 2016. Severe frostbite and altitude sickness have left more than 30 climbers on Mount Everest needing medical help. 

Two Indian climbers have also been reported missing in the mountain's so-called "death zone" near the summit.

With the mountain open again this season, which runs from March until the end of May, climbers have been taking advantage of good conditions in large numbers, with nearly 400 reaching the summit from the Nepalese side since 11 May.

"They were always extremely well-prepared, they trained really, really hard before each event that they did. There was never any incident before this one."           - Aletta Newman, Maria Strydom's sister.

Dutch climber Eric Ary Arnold died on Friday after reaching the summit. The next day, the 34-year-old Australian, Maria Strydom, also died while descending from the peak.

Arnold had tweeted that he had made it to the summit, but he is said to have complained of feeling weak as he descended, despite having bottled oxygen, and he died on Friday night.

The bodies, which are at 8,000 metres, had yet to be retrieved on Sunday. 

The incident highlights the dangers of the world's highest mountain, though many continue to make it to the summit.