The bodies of two men aged 32 and 36 and a third aged 56 were found on Saturday evening, with a 28-year-old man still missing, police said.
The avalanche came after several days of heavy snowfall which saw the army called in to secure roads and buildings and help with a number of evacuations.
The accident took place at an altitude of 1,800 metres (6,000 feet) as the pair from the Morillon ski resort "were working on an avalanche prevention programme", one of the experts said.
Meanwhile, two employees at a ski resort in the French Alps died on Sunday when the avalanche-control charges they were trying to set accidentally went off, mountain rescue experts said.
Controlled explosions are carried out before the slopes open to mitigate the risk of larger avalanches.
They were working with the explosives when the accident happened, local police said following an initial investigation.
Forecasters at Meteo France had warned of a high risk of avalanches in the Savoie and Haute-Savoie regions following fresh overnight snowfall.