Thirty-five people were rescued after the storm on Monday evening, including 24 Senegalese, six French, two Germans, two Swedes and one Guinea-Bissau national, according to Dakar's fire brigade chief, Col. Michel Diatta.
Most were stranded on Madeleine Island and have been taken to a hospital, he said.
Interior Minister Aly Ngouille Ndiaye told private radio station RFM early Tuesday that four people had died. He said they were Senegalese, among them national parks staffers.
RFM later reported that two more Senegalese had succumbed to their wounds and died, citing medical officials.
It was not immediately clear if everyone was accounted for.
President Macky Sall sent condolences to the families of the victims and called for attention to security during this period of bad weather. It is the rainy season in Senegal.
The uninhabited island is popular with tourists who go on daily trips to see a diverse bird population and have picnics.
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