August is the height of the climbing season on Mont Blanc, where even in the warmest months fierce storms can strike quickly. Several mountaineers have died already this summer — including at least one experienced guide — and local officials say they fear many people come to Mont Blanc ill-prepared for the dangers.

The group of five climbers and a guide were reported missing overnight when they failed to return to a refuge after a planned trip to the Aiguille d'Argentiere, which tops out around 3,900 meters (12,800 feet). Mont Blanc, in addition to its primary peak, contains some 200 summits.

The bodies of five of the climbers were located Wednesday, while a sixth has not been found, said Jean-Marc Peillex, mayor of Saint-Gervais, a town at the foot of Mont Blanc.

Search and rescue teams headed up the slopes and a helicopter took advantage of brief windows of calm weather to fly over the area, said Christophe du Payrat, a local official.

Mont Blanc touches France, Switzerland and Italy, and thousands try to reach its summit each year.