Four climbers have died after a slab of ice from a frozen waterfall detached from a mountainside near Italy’s northern border with Switzerland, Alpine rescue authorities said.

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

The head of the Val d’Aosta Alpine rescue service, Adriano Favre, told Italian media the sudden rise in temperatures on Wednesday might have caused the chunk of ice to melt enough for it to detach.

The surviving climber had apparently reached a ledge above where the frozen waterfall cracked off, with the other four climbers below.

The survivor was rescued by Alpine teams.