The tourists had accessed the Panoramic Mont Blanc cabins, open from June to the end of September, from either the Helbronner in Italy or the Aiguille du Midi in France.
The two peaks have their own cable car system connecting them to their nearby villages.
The French Téléphérique de l'Aiguille du Midi connects the peak of Aiguille du Midi to the village of Chamonix, while the Italian Skyway Monte Bianco connects the peak of Pointe Helbronner to the village of La Palud, just north of Courmayeur near the Mont Blanc Tunnel.
The Panoramic Mont Blanc cable car tourist attraction linking the two countries was opened in 1958.
There are 12 groups of three cabins which seat four people each.
They are pulled by a haulage rope of 10,200 metres in a single loop.
The cabins run from the Aiguille du Midi station over the Vallée Blanche glacier and the Glacier du Géant glacier to the Helbronner station.
Although the cables sag by some 255 m, the cabins still have a clearance of some 300 m to the glacier underneath.