A British climber on Sunday found the bodies of six mountaineers in the French Alps who fell to their deaths in one of the worst accidents in the region in years.
The dead included a 16-year-old boy, two men and three women aged between 42 and 64, all French nationals, said regional prosecutor Remy Avon, who did not disclose their identities.
He also distanced himself from earlier reports suggesting the group fell following an avalanche of snow and stones.
"A priori, it is not an avalanche.... For the moment, we do not know the reason" for the fall, he said, explaining that officials in the area have opened an investigation into the tragic accident.
The mayor of the nearby village of Villar d'Arene, Xavier Cret, had earlier told AFP there may have been "a slide of snow and stones" that caused the mountaineers to fall to their deaths.
The climbers set out Saturday at around 0600 GMT under a clear sky carrying the gear necessary for a steep climb, including ice picks, clamps and clothing suited to high altitude physical exertion, Avon said.
Two separate groups were roped together, a common safety practice to ensure that someone who slips can be held up by their climbing companions.
The first group approached a peak at an altitude of 3,217 metres (10,500 feet) called Plate des Agneaux, then fell between 150 and 200 metres back down the mountain, leaving traces of shifting earth above them, Avon said, citing reports from the preliminary investigation.
The prosecutor speculated the first group may have forced the trailing group to fall, but also noted it was possible the two groups fell independently.
The bodies were found on the Neige Cordier summit at 3,000 metres and taken by helicopter to Villar d'Arene, according to the mayor.
The British hiker stumbled across the bodies as he was taking the same route that they had followed a day before, mountain rescue police said.
Their bodies were found in a narrow, steep-sided ravine that is regularly used by skiers in winter and climbers in summer.
Cret, the mayor, said the group was tied together with two ropes when found.
He explained that any fall in that part of the Alps could have "serious consequences," but noted there have been few accidents in the area where climbing conditions are not particularly difficult.
But the accident with six fatalities is one of the worst such cases in recent years in France. In June 2007, five climbers from the same family died after a fall on a nearby mountain.
The dangers of mountain climbing were further highlighted in Switzerland on Sunday, where a 42-year-old Italian died trying to ascend the 3,370 metre Galenstock peak.
The man's two companions aborted the climb due to fog and a strong wind, but the victim decided to press on and later fell some 200 metres for reasons that were not immediately clear, area police said in a statement.