Five climbers — including a father and his 17-year-old daughter — have died after being caught in an avalanche in the Italian Alps.

Alpine rescuers said the German climbers had set out on Saturday, Nov. 1, to scale Cima Vertana in the Ortler mountain range near the Italian village of Solda, per the Associated Press, the BBC and Reuters.

An avalanche struck at around 4 p.m. as they were headed for the mountain’s summit, located at around 11,500 feet. Rescuers said they are not sure why the group were still on their way up at that time, as it was considered late to still be climbing.

The outlets reported that that the climbers were traveling in different groups and were not climbing together. A group of three “was fully swept away by the avalanche,” the Alpine rescue service told the BBC.

“They had been dragged to the lower part of the gully where the avalanche occurred,” Alpine rescue spokesman Federico Catania told the AP. “Rescue teams are now returning to the valley, also considering the worsening weather conditions at high altitude.”

Rescuers reported that two men survived the incident and were transported to a Bolzano hospital by helicopter. The survivors were the ones who alerted rescuers to the incident, according to the BBC.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories.

Olaf Reinstadler, a spokesperson for the Sulden Mountain Rescue Service, told German media the avalanche may have been caused by recent snow drifts, which had not bonded to the ice below, per the BBC. Reinstadler added that the weather conditions were good for the trip, but said it was unusual for the climbers to still be out in late afternoon as it would have been dark by the time they got off the mountain.

Rescue operations were paused on Saturday night due to fog and low visibility, and helicopters did not take off again until Sunday, per the BBC. Rescuers and canine units were airlifted to about 8,530 feet before beginning their operations on foot.

The region, part of the Italian Alps close to the Swiss border, is popular with mountaineers, with peaks reaching 12,811 feet.

According to the AP, avalanches are a common cause for accidents in the Alps, particularly among ski mountaineers or freeriders.

The outlet reported that some analysis shows that the number of accidents has increased in recent years, in part, because more climbers travel to backcountry areas almost immediately after snowfall.