The total number of deaths caused by Cyclone Chido in the Mayotte region abroad will not be known for some time, the authorities said.
“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.
According to a preliminary report by the authorities on Monday morning, 20 deaths have been confirmed so far, broadcaster France Info said.
More than 250 injuries were recorded.
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.
Retailleau said most of the poor houses were destroyed by the hurricane. Thousands of homes are without electricity, and there are also problems with the water supply and the telephone network.
Roads are closed and some areas are being cut off. In the island's capital, Mamoudzou, the hospital and schools were also hit, according to reports.
Rescuers in the overseas region urgently searched for survivors on Monday.
Colonel Alexandre Jouassard of the Inter-Ministerial Emergency Center told the public television channel France 2 that there is still hope of finding people alive. “The next few hours are very important. We have used teams that specialize in finding debris,” said Jouassard.
Even several days after the storm, victims are still being found, he said, adding, “This is our priority.”
At the same time, local healthcare provision is challenging. Acting French Health Minister Geneviève Darrieussecq described the situation on France 2 as “deeply degraded, with a badly damaged hospital and non-functional health centers.”
She emphasized the need to be vigilant in terms of communicable diseases, which may arise from consuming contaminated water or spoiled food.
Since hitting Mayotte, Chido is on its way to Mozambique on the African continent, where the storm reached speeds of up to 240 kilometers per hour.
According to the United Nations Children's Fund (UNICEF), it destroyed and damaged several homes, schools and health facilities in the northern province of Cabo Delgado.
