Four people have been reported dead and two others are missing in four days in Mount Everest.

Climbing season is about to end in the world’s highest peak. According to CNN, the deaths happened on Thursday, Friday, and Saturday.

On Thursday, 25-year-old crew member Phurba Sherpa fell to his death while fixing a route near the summit. The sherpa people are an ethnic group in Eastern Nepal that have lived in the country’s high altitudes and most mountainous region for generations. They have served as guides to foreigners attempting to climb the trecherous mountain.

On Friday, 36-year-old Eric Arnold from the Netherlands died while heading back after a successful climb. No official reports have been released on what caused the death, but it is believed that he died of a heart attack.

Then, on Saturday, 34-year-old Australian professor Maria Strydom, suffered altitude sickness and died at the final camp before the summit. According to her sister Aletta Newman, the family became aware of Ms Strydom’s death online, and have been getting conflicting reports.

Mr Arnold and Ms Strydom were part of the same expedition team Seven Summit Treks.

“We haven’t had anyone from that company talking to myself directly, they haven’t called us to inform us of anything,” said Ms Newman. “A number of family members have tried to call around and get information. We’ve even read in newspapers and online different accounts of what actually had happened.”

On Sunday, 44-year-old Subash died at Base Camp II from altitude sickness. He was reportedly part of a team of four climbers and four sherpas that saw two members, identified as Paresh Chandra Nath and Goutam Ghosh, go missing on Saturday. “It is not clear what happened. We believe the weather suddenly deteriorated at some point, and the team lost direction,” said Wanchu Sherpa about the incident.

“We are trying to communicate with other expedition teams around that level to locate the missing climbers,” said Nepal Tourism Department official Gyanendra Shrestha.