An avalanche swept over a group of European climbers in the French Alps on Thursday, killing at least nine people and leaving four missing.
Rescuers said they had suspended their search for the four unaccounted for following the early morning avalanche on Mont Maudit, which translates as "Cursed Mountain", but that it would likely resume on Friday.
"The avalanche zone has been entirely surveyed. The searches will resume tomorrow depending on the weather," local police Colonel Bertrand Francois said.
Francois said nine people were known to have died in the accident: three Britons, three Germans, two Spaniards and a Swiss.
The four missing climbers were believed to be two Britons and two Spaniards, officials said.
Nine more climbers were lightly injured and treated at a local hospital.
After flying over the scene in a helicopter, Interior Minister Manuel Valls warned that it may not be possible to recover the missing climbers.
"The mountain does not always release its victims," Valls told a press conference. "Searches will probably continue of course, under ice and snow conditions that are difficult."
Asked about the cause of the accident, Valls said: "The investigation is beginning under the authority of prosecutors."
Italian rescuers were brought in to assist France's PGHM high-mountain group in the search in the Mont Blanc massif at a height of more than 4,000 metres (13,100 feet).
Delfino Viglione, local director of mountain rescue for the border patrol police, told AFP the Italians had contributed a dog rescue team, four military personnel and two mountain rescuers to the search operations.
"It is a tough, steep part of the mountain. The wind probably led to an accumulation of snow that dislodged when the climbers passed," he said.
"Mont Blanc can be problematic even in the summer. You should never lower your guard. Unfortunately these tragedies happen often."
One of the injured sounded the alert at around 0325 GMT after the avalanche on Mont Maudit, the massif's third-highest peak, which rises to 4,465 metres (14,650 feet) and is considered one of the more difficult paths to the summit of Mont Blanc, Europe's highest mountain.
Officials said the victims had been in a group of 28 people, including guides, who had left a base at 3,600 metres at around 1:30 am local time (2330 GMT Wednesday) for the climb.
Francois said it was believed the avalanche was caused when a climber caused a sheet of snow and ice to break off the mountainside.
Weather service Meteo France said there were strong winds in the area on Thursday, reaching up to 70 kilometres (43 miles) per hour.
It is the deadliest climbing disaster in France since August 2008, when eight climbers -- four Germans, three Swiss and an Austrian guide -- were swept away after blocks of ice broke off Mont Blanc du Tacul, prompting an avalanche.
Some 20,000 climbers attempt to reach the summit of Mont Blanc every summer, with up to a 500 a day during peak times.
Experts said the increasing number of climbers was boosting risks.
"The increased use is a danger in and of itself because it slows down the rope parties," said Philippe Descamps, the secretary general of the Petzl Foundation, which promotes mountain safety and the environment.
Increased numbers also give climbers a false sense of security, he said.
"Because we are many, we are much less careful," he said, adding that increased numbers "give a sense of security and can reduce alertness."
Denis Crabieres, the head of France's National Union of Mountain Guides, also said increased traffic heightened risks on the mountainside.
"A significant number of people in the same area causes behaviour that we wouldn't see otherwise," he said.
"This can make rope parties pass each other in unsuitable terrain. It's a bit like when there a lot of people on the road," Crabieres said.
Source: AFP Global Edition