The snow slide struck the skiers at around 15:00 local time (13:00 GMT) near the town of Briancon in the Ecrins National Park.
Eight others were also swept away but survived. One person was airlifted to a hospital in Grenoble for treatment.
The national park is popular with skiers and mountaineers, with peaks of over 3,000m (9,842ft).
Officials told the Associated Press that seven members of the group were currently staying in a refuge building near the site until emergency services could rescue them.
Three tourists, two Austrians and an Italian, have been killed in an avalanche in the French Alps.