KATHMANDU, Nepal — Two climbers have died after showing signs of altitude sickness while descending Mount Everest.

Eric Arnold, 35, of the Netherlands died near the South Col on Friday night, said Pasang Phurba of the Seven Summit Treks agency in Kathmandu.

Maria Strydom, an Australian, died on Saturday, according to media reports.

Arnold had enough bottled oxygen with him as well as climbing partners, but he complained of getting weak and died before he was able to come down to a lower altitude, Phurba said.

Arnold, from Rotterdam, tweeted Friday, “Mountain climber Eric Arnold reaches the summit of Mount Everest at the fifth attempt,” but he acknowledged that “two-thirds of the accidents happen on the way down.”

Meanwhile, Monash University in Melbourne, Australia, posted news of Strydom’s death on Facebook. Strydom, a finance lecturer, reached the summit Friday but died after showing signs of altitude sickness while descending Saturday afternoon.

An earlier post on the business school’s website said Strydom and her husband were attempting to climb the Seven Summits, the highest peaks on the seven continents.

In addition, a 45-year-old woman from Norway, Siv Harstad, was helped down from the top of Everest on Saturday by two Sherpa guides after suffering from snow blindness, the Norwegian news agency NTB said.