PORT-AU-PRINCE, Haiti--Flooding from Tropical Storm Fay killed four people in Haiti and the Dominican Republic, and authorities warned Saturday that the storm could reach hurricane strength as it barreled toward Cuba.

Florida's Gov. Charlie Crist declared a state of emergency and said Fay threatened the state with a "major disaster." Forecasters said Fay could bring hurricane-force winds to the Florida Keys as soon as Monday.

The U.S. National Hurricane Center in Miami said that on Saturday afternoon the storm was located about 60 miles (100 kilometers) south of Guantanamo, Cuba. It was heading west at about 16 mph (26 kph), and maximum sustained winds had decreased slightly to 40 mph (65 kph).

A man died Saturday in Haiti while trying to cross a river in Leogane, south of Port-au-Prince, said Marie Alta Jean-Baptiste, head of Haiti's civil protection department. No further information was immediately available.