The incident, which occurred at 04:00 a.m. local time (0200 GMT), killed two Italian women aged 37 and 41 years old respectively and the guide was hospitalized. A fourth climber was missing.
The report said a fall of an ice block provoked the avalanche.
“If the weather is good, the zone remains very dangerous because the snowpack is very unstable,” the gendarmerie was quoted by the daily Le Parisien as saying.
“We were forced to limit the number of rescuers sent there. Only two rescuers can approach the area via helicopter,” it added.