At least 14 people have died in Mayotte after a powerful cyclone hit the French Indian Ocean territory, officials said on Sunday. Authorities warned it could take days to know the full extent of the damage and casualties.

Rescue teams and supplies are being sent by air and sea, but their efforts are being slowed by damage to airports and power lines. Mayotte, which already struggles with clean water shortages, is facing even more challenges after the storm.

A provisional list counted 14 deaths, according to authorities. The mayor of Mayotte’s capital, Mamoudzou, Ambdilwahedou Soumaila, said nine people are critically injured and in hospital, while 246 others were seriously hurt.

The island’s 320,000 residents had been told to stay indoors as Cyclone Chido approached. The storm brought winds of at least 226 km/h, destroying shantytowns and knocking down electricity poles, trees, and poorly built homes. Acting Interior Minister Bruno Retailleau said the damage is severe, and the death toll could rise further.

Retailleau will visit Mayotte on Monday with 160 soldiers and firefighters to help the 110 emergency workers already sent to the island. Medical supplies and equipment are also being delivered from La Reunion, another French territory, to support the recovery efforts.

Authorities are continuing to assess the situation and organize relief operations.