Miami, Florida - Tropical Storm Alex, the first named storm of the Atlantic hurricane season, gained a bit more force Sunday as it headed toward Bermuda after killing three people in Cuba and causing flooding in parts of Florida.

Alex reached tropical storm force after strengthening off Florida's east coast Sunday.

The U.S. National Hurricane Center said Alex had maximum sustained winds of 105 kph (65 mph) and was centered about 640 kilometers (395 miles) west of Bermuda late Sunday afternoon.

It was moving to the east-northeast at a brisk 44 kph (28 mph) and was expected to pass near or just north of Bermuda on Monday. A tropical storm warning was in effect there. Forecasters said it could drop 25 to 50 mm (1 to 2 inches) of rain across Bermuda beginning late Sunday and into Monday.

National Security Minister Michael Weeks said emergency services were monitoring the storm.

In Cuba, Alex killed three people, damaged dozens of homes in Havana and cut off electricity in some areas, authorities reported.

Parts of South Florida experienced road flooding from heavy rain and wind Saturday. Officials in Miami were towing stranded vehicles from flooded roadways.

Miami Beach Mayor Dan Gelber said the storm tested the system of drainage pumps the city recently installed as climate change has increasingly made flooding an issue in the low-lying area.

"We moved the water off pretty quickly, but in some areas, obviously, it was really challenging," Gelber said. "There were some problems getting through on some streets, one of the main arteries was unpassable, but by and large water is dissipating."

Alex partially emerged from the remnants of Hurricane Agatha, which made landfall on Mexico's southern Pacific coast last week, killing at least nine people and leaving five missing as it moved over land.

The Atlantic hurricane season officially began Tuesday. This is an unusually early start to the storm season but not unprecedented for Florida.