Hurricane Irma wreaks major damage in Caribbean
The four “most solid” buildings on Saint Martin, shared by France and the Netherlands, were destroyed, French Interior Minister Gérard Collomb said.
Communications between Paris and Saint Martin and Saint Barthélemy are down.
The category five hurricane, the highest possible level, has sustained wind speeds reaching 300km/h (185mph).
The most powerful Atlantic storm in a decade first hit Antigua and Barbuda, before moving on to Saint Martin and Saint Barthélemy.
It is expected to move on towards Puerto Rico and the Dominican Republic. In the US, Florida’s Key West area has ordered a mandatory evacuation.
The French government said earlier it was worried about thousands of people who had refused to seek shelter on the islands.
In a statement, the interior minister said France was sending three emergency teams to the islands, two from France and one from Guadeloupe.
There was no news of possible casualties, he said, adding that “more rustic structures” had “probably been completely or partially destroyed”.
French Overseas Territories Minister Annick Girardin said the hurricane had caused major flooding in low-lying areas, and coastlines were being “battered extremely violently” by the sea.