Two dead and two missing near the summit of Mount Everest

Two people died from elevation sickness and two have gone missing as hundreds of climbers make their push toward the summit of Mount Everest, an often-treacherous climb in the Himalayas of Nepal.

The first casualty was confirmed on Saturday after Dutch mountaineer Eric Arnold, 35, complained of weakness and died while attempting a descent to lower elevations Friday night. The mountaineer had reached the summit on his fifth attempt, his Nepal-based expedition reported.

“Two-thirds of the accidents happen on the way down,” Arnold had told a local radio station in the Netherlands before the climb. “If you get euphoric and think ‘I have reached my goal,’ the most dangerous part is still ahead of you.”

Another member of his 40-person expedition also perished several hours later after succumbing to altitude sickness. Maria Strydom was an Australian climber who worked as a lecturer at Monash University, according to the Associated Press.

In a season that saw at least 30 climbers suffer from frost bite and other injuries on their climb through the mountains of Nepal, two Indian climbers, Paresh Nath and Goutam Ghosh, who were last seen near the summit of Mount Everest on Saturday, were reported missing, according to the AP.

Since the 2016 climbing season began on May 11, nearly 400 people have successfully reached the world’s highest mountain. But hard-to-predict weather and dangerous conditions can cause problems for climbers as they head to and from the peak, which is 29,035 feet high.

The Nepalese routes to Mount Everest were closed last year following a devastating earthquake that killed thousands of people before the climbing season began. During the May 2014 climbing season, 18 people were killed when an avalanche struck the Everest Base Camp.