Hurricane Dennis gathered strength with extremely dangerous 240-kph winds as it bore down on central Cuba todau and was on track for the US Gulf of Mexico, where oil companies began evacuating workers from rigs.
Forecasters at the US National Hurricane Centre said the eye of Dennis would hit Cuba today and head into the eastern Gulf early tomorrow.
Dennis is the strongest Atlantic hurricane to form this early in the season since records began in 1851, the centre said.
Chevron said it evacuated all workers from the central and eastern Gulf where oil and gas rigs could be at risk. Shell Oil said it evacuated 555 workers from Gulf operations as a precaution, and that more evacuations were expected.
Hurricane winds and heavy rainfall knocked down power lines and communication towers in southeastern Cuba, but the island of 11 million braced for worse as Dennis headed for landfall near the city of Cienfuegos.
At the nearby Bay of Pigs, buses evacuated residents after they secured their homes, taped up windows and collected valuable possessions.
Panicky inhabitants of Havana, the capital of 2.3 million, lined up at gasoline stations and bakeries to stock up with fuel and bread. Authorities suspended all school classes in Cuba and evacuated 200,000 people from coastal areas, including hundreds of tourists on holiday on outlying islands.
The hurricane was expected to barrel through Cuba and out into the Florida Straits anywhere between Havana and the beach resort of Varadero, Cuban forecasters said.