A German mountaineer died when he fell climbing the Lagginhorn peak of 3,971 metres in the Swiss Alps canton of Valais.
"A group of seven German climbers set off to climb Lagginhorn," police in Valais said in a statement, adding they were not roped together.
"Around 100 metres from the summit, at an altitude of 3,850 metres, one of them lost his balance and fell several hundred metres."
The climber, who has not yet been named, died on the spot.
In another incident, three climbers who were roped together died trying to climb the Meitin glacier.
One of the climbers apparently fell and dragged his two companions with him, police in Valais said in a separate statement.
The group slid down the glacier for several hundred metres, smashing into the rocks, despite being equipped with ice axes and crampons.
The three climbers have not yet been identified.