The total number of deaths caused by Cyclone Chido in the Mayotte region abroad will not be known for some time, the authorities say.
“It will take days and days,” said France's acting interior minister, Bruno Retailleau, when he visited the islands on Monday.
The local prefect, François-Xavier Bieuville, told the local radio station on Sunday night that he believed “certainly hundreds” of people had been killed in the storm.
The French overseas territory of Mayotte is located in the Indian Ocean between the coast of the southeastern African country of Mozambique and the island nation of Madagascar.
About 310,000 people live on the islands. Cyclone Chido swept over Mayotte on Saturday with winds of more than 220 kilometers per hour, leaving a devastating trail.