Heavy rains and high winds are pounding Jamaica - heralding what is expected to be a devastating hurricane.
The government has told people to take shelter
The authorities have urged 500,000 people to evacuate coastal areas, to escape the worst of Hurricane Ivan.
It has already left a massive trail of damage in the Caribbean, killing at least 26 people, mostly in Grenada.
Ivan is bristling with 145mph (230km/h) winds. It is being rated as category four, on a scale of five, but could gain strength as it nears Jamaica.
"We have to prepare for the worst case scenario. Let us pray for God's care," said Prime Minister PJ Patterson, pleading for people to evacuate to special shelters.
Officials said only a few hundred people had so far gone to the shelters.
At 1800 GMT the hurricane - dubbed Ivan the Terrible by Jamaicans - was about 85 miles (140km) south-east of Kingston, the US National Hurricane Center said.
Moving at a speed of about 12mph (19km/h), it was due to reach Jamaica late on Friday or early on Saturday morning, it said. The Cayman Islands are also in its path.
"Ivan could become even stronger as it nears Jamaica," it warned, adding that heavy rains could cause "life-threatening flash floods and mudslides".
Hospitals are on full alert and all schools, shops and airports have closed.
"This one looks like a killer. If it follows the same path, a lot of us will die," said Kingston resident Jefferson James.
The BBC's Declan Lawn, in Jamaica, says a lot of the country's housing is very basic, consisting of wooden shacks and lean-tos.
There have been long queues at supermarkets with people stocking up on water, fuel, torches and batteries.
The authorities have made it clear that they will use the police and army to deal with looting and civil disorder.
Tourists have been leaving the islands in droves. British tour operators have arranged for 2,600 holidaymakers to be airlifted to the Dominican Republic.
Correspondents say this threatens to be the worst natural disaster to hit Jamaica for 50 years.
Cuba and parts of Haiti also face hurricane warnings, and the south-eastern United States is also under threat.
Residents and tourists in Florida Keys are being evacuated once again, after two major hurricanes in the last month.
So far the place hardest hit by Hurricane Ivan has been the tiny island of Grenada.
The first deliveries of aid supplies from abroad have arrived, but the International Red Cross said about 60,000 of Grenada's 95,000 inhabitants are homeless, as it launched an emergency appeal for donations.
Grenada's Prime Minister, Keith Mitchell, whose official residence was destroyed, told the BBC the island was "90% devastated" and that he had declared a national disaster.
PREDICTED PATH OF HURRICANE IVAN