Three people died on Thursday while climbing the Piz Bernina mountain on the Swiss-Italian border. On Wednesday, a German woman also died on the same peak.
The three climbers were at 3,600 metres when they fell 300m at around 7.30am on Thursday morning, Graubünden police said in a statement.
Witnesses called the Rega air rescue service which found the bodies. However, owing to falling rocks their bodies could only be helicoptered off the mountain on Friday morning.
On Wednesday, another person died on the same mountain. A 32-year-old German woman was climbing with a group on the Piz Bernina when she slipped and fell around 600m just after 7am on Wednesday morning, police said. Rega air rescue services also recovered her body after being contacted by a member of the group.
Ueli Mosimann, head of safety at the Swiss Alpine Clubexternal link, told the Basler Zeitungexternal link that the heatwave was causing difficult conditions in the mountains. Not only is there a risk of storms, but danger also comes from melting glacier snow, he said.
Mountain sports are extremely popular in Switzerland, but are also considered the most dangerous. On average, around 100 people die every year in the Swiss mountains hiking and climbing. According to the Swiss news agency, 16 people have died in the Swiss Alps since the beginning of July.