Three Britons were among nine climbers killed in a "catastrophic" alpine avalanche, according to the French authorities.
A major rescue operation was launched following the disaster on Mont Maudit, in the Mont Blanc range, near Chamonix.
The Prefecture de la Haute-Savoie said that three Britons, two Spaniards, three Germans and one Swiss person also died.
Two British climbers and two Spaniards who were reported missing after the avalanche were confirmed by local police as being alive and well when they presented themselves at the police station in Chamonix this evening.
The four survivors had changed their climbing route on Mont Maudit, police said. All those believed to have been missing have now been accounted for but police said they would continue searching the area in the morning.
Several dozen gendarmes and other rescuers along with two helicopters worked to pull the dead and injured from the mountain after the alarm was raised at 5.25am.
French interior minister Manuel Valls visited the area and flew over the avalanche site.
Speaking at a press conference afterwards, he said: "We are still searching for those who have disappeared.
"My thoughts are with those victims, with the British and Spanish and German victims, Swiss victims, and my thoughts are with their families who have discovered this painful tragedy. It is a personal one.
"Regarding the circumstances of this avalanche, as you know the investigation is under way and the prosecutor general is looking into this.
"We have seen many accidents on the Mont Blanc mountain but we should note that the number of victims and those who have disappeared and the injured is very high."
A spokeswoman for the prefecture said the local gendarmerie were alerted at 5.25am that two groups of climbers were in trouble on the northern face of Mont Maudit at 4,000m.
She said that at 5.45am the emergency services were told it was a "slab" avalanche which had hit several groups of mountaineers who were roped together.
Some of those caught in the avalanche were supervised by professional mountaineering guides but others were climbing independently.
The spokeswoman said nine people were taken to hospital in Sallanches with minor injuries and a chapel had been established in the hospital in Chamonix to help families involved in the tragedy.
A total of 28 people left a climbing hut to attempt the route.
The spokeswoman said some had crossed the path of the avalanche before it hit and others were able to turn back.
A British foreign office spokesman said: "We are aware of the avalanche in the French Alps near Chamonix today and reports three British nationals have died.
"We are urgently seeking information from the rescue authorities, but as yet do not have official confirmation of these deaths. We are aware of five missing British nationals and are urgently working to establish their whereabouts."
The former general secretary of the British Mountaineering Council and respected climber Roger Payne was among those who died in the avalanche.
Dave Turnbull, the current chief executive of the council, said: "The mountaineering world is shocked and saddened to learn of the tragic death of Roger Payne.
"Roger was one of the UK's most enthusiastic and respected climbers, with a track record of Alpine and Himalayan mountaineering stretching back to the 1980s."
Chamonix-based mountain guide Richard Mansfield said the route where the accident happened was the second most popular to the top of Mont Blanc.
He said: "It's a very beautiful area and a common route, but it can have very serious consequences, particularly due to avalanches."
PA