Updated

Alpine emergency crews say four mountain climbers have been killed after a slab of ice detached from a mountainside near Italy's northern border with Switzerland.

A fifth climber survived the incident Thursday in Gressony-Saint-Jean, in the Val d'Aosta region.

The head of the Val d'Aosta Alpine rescue service, Adriano Favre, told RAI state television the climbers were likely experienced given the peak was a difficult one to climb. He suggested a sudden rise in temperatures on Wednesday might have caused the chunk of ice to melt enough for it to detach.