A group of hikers had been swept up in an avalanche while they were outside a ski area, at the gateway to the Mercantour National Park.
A group of six people, five hikers and their guide, left mid-morning on Friday. The avalanche alert was triggered around noon.
A provisional list of casualties Tweeted by police showed that four hikers lost their lives in the accident while one person was lightly wounded and another was reported missing.
The avalanche risk in the Alpes Maritime mountain range was increased to 5 due to weather conditions and heavy snowfall in recent days.
Since the start of the winter season in November 2017, 16 people have died due to avalanches, according to local reports.