Emergency officials said another eight people have been injured, and 15 remain missing.
At least six people have been killed after being caught in an avalanche sparked by the collapse of a glacier in the northern Italian Alps.
Emergency officials said nine others were injured in the collapse, with two people suffering serious injuries.
Rescue teams using helicopters and drones have been working through the night searching for 19 still missing.
Video of the incident showed an ice mass collapsing down the slopes of Marmolada, the area’s highest mountain.
“An avalanche of snow, ice and rock which in its path hit the access road when there were several roped parties, some of which were swept away,” emergency services spokeswoman Michela Canova said. “The definitive number of mountaineers involved is not yet known,” she added.
The injured hikers, including one person left in critical condition, were taken to several hospitals around the area, rescue officials said.
It isn’t immediately clear what caused the section of the glacier, called a serac, to collapse.
But Walter Milan, a rescue service spokesperson, told state TV the area has been experiencing unusually high temperatures in recent days.
“The heat is unusual,” Mr Milan said, noting temperatures have reached 10C at the glacier’s peak in recent days.
“That’s extreme heat,” he said. “Clearly it’s something abnormal.”
Reinhold Messner, an Italian mountaineer, told La Repubblica newspaper the glacier has been receding for several years due to the impact of global warming.
“There is hardly any ice left,” Mr Messner said. He noted glaciers occasionally collapse “due to gravity,” but said the reason for the glacier’s retreat “is the global heat, which causes glaciers to melt”.