The death toll elsewhere in the Caribbean rose to 37, the latest victim an 8-year-old boy who died Friday of head injuries sustained when the storm destroyed his home in Grenada on Tuesday.
The eye of the "extremely dangerous" 150-mph Ivan was expected to hit land around 2 a.m. local time, meteorologist Jack Beven said from the U.S. National Hurricane Center in Miami.
He said it was passing south of Kingston around 8 p.m. local time, sparing that densely populated capital of 1 million people the brunt of its wrath.
Reports of sporadic gunfire and looting in Kingston reached the emergency management agency, said spokeswoman Nadine Newsome, but police could not confirm that.
Howling winds and sheets of horizontal rain crashed around the eastern end of the blacked-out island after utility officials turned off the power to minimize damage to plants.
Prime Minister P.J. Patterson declared a public emergency Friday afternoon and pleaded with the half million people considered in danger — about one in five islanders — to get to shelters. But most residents refused to leave for fear that abandoned homes would be robbed.
"I'm not saying I'm not afraid for my life but we've got to stay here and protect our things," said Lorna Brown, 49, pointing to a stove, television, cooking utensils and large bed crowded into a one-room concrete home on the beach at the northwestern resort of Montego Bay.
Cuba declared a hurricane watch across the entire island Friday after its leader, Fidel Castro, went on national television warning residents to brace themselves. "Whatever the hurricane does, we will all work together" to rebuild, he said.
In South Florida, long lines reappeared at gas stations and shoppers swarmed home building stores and supermarkets. Forecasters said Ivan could tear through the Keys as early as Monday though there was still a chance the storm would instead move out into the Gulf of Mexico.
"I have been through a few hurricanes and I haven't seen people leaving like they are leaving," Key Largo resident Mike Winker told CBS News Correspondent Brian Andrews. "There seems to be a sense of urgency of everyone boarding up and getting out of town."
Farther south, in areas already struck by Ivan, authorities discovered more bodies along Venezuela's flooded coast and in devastated Grenada.
"When dogs interfere with garbage bags and strew the contents all over the place — that's what Grenada looks like," Trinidadian leader Patrick Manning said after visiting the island.
In Jamaica earlier, awed onlookers stood transfixed on the seaside Palisadoes Highway near Kingston's airport as 23-foot waves crashed to shore, thrusting rocks and dead tree branches more than 100 feet into the road.
"I've lived here all my life and I've never seen anything like this," said businessman Chester Pinnock.
"This is going to be disastrous, we could have hundreds dead. Hurricane Gilbert was a puppy compared to this," he said. Gilbert killed dozens of Jamaicans and devastated the island when it struck as a Category 3 storm in 1988.
Ivan is a large Category 4 hurricane — out of a top scale of 5 — with hurricane-strength winds extending 60 miles and tropical-force winds another 175 miles. Jamaica is only 145 miles long and 50 miles at its widest.
"What we're experiencing now is only the beginning," Jamaica's prime minister said in an address to the nation. "Residents living near coastal areas must evacuate before it's too late. ... I cannot stress too strongly that Ivan is a dangerous hurricane."
But only 5,000 people moved into shelters island-wide, emergency management director Barbara Carby said. The government had asked 500,000 to flee.
In Montego Bay, where hundreds of tourists were stranded, the Barnett River overflowed its banks, putting some businesses on Bouge Street four feet under water and, farther inland, flooding roads and farmlands. Drenching rain washed away the main northern coastal road, the A1, a couple of miles outside Montego Bay.
The British Royal Navy frigate HMS Richmond, which rushed to Grenada's rescue Wednesday, was speeding to Jamaica along with a supply ship, Commander Mike MacCartain told the BBC.
Jamaicans can expect to feel the effects of the punishing hurricane through most of Saturday, said Lt. Dave Roberts, a Navy meteorologist at the Hurricane Center in Miami. It was projected to exit the island around Montego Bay, pass the Cayman Islands and cross over Cuba before taking aim at southern Florida.
At 8 p.m. local time, Ivan was centered about 45 miles south-southeast of Kingston, moving west-northwest near 11 mph.
East of Jamaica, in neighboring Haiti, people expressed relief after Ivan's passing spared them further catastrophe in a year that brought a bloody rebellion and deadly floods.
"First we had a political hurricane, then an economic hurricane, and now with the natural hurricane, we're just glad God saved us," said Jude Vante, 32, an unemployed mason in low-lying Les Cayes, on the southern peninsula.
Still, heavy rains pounded Les Cayes, leaving several homes knee-high in sand and water. Crashing waves destroyed at least two houses and crops in the Artibonite Valley, north of Port-au-Prince, and floods damaged a dozen homes in the northern city of Cap-Haitien, the Civil Protection government agency reported.
Ivan became the fourth major hurricane of the Atlantic Season on Sunday, and on Tuesday damaged dozens of homes in Barbados, St. Lucia and St. Vincent before making a direct hit on Grenada, which it left a wasteland of flattened houses, twisted metal and splintered wood. It damaged 90 percent of homes there, tossed sailboats to shore and set off frenzies of looting among some of the 100,000 residents left without electricity, water and telephone service.
"Galvanized sheeting spread over the land, no trees have leaves, many houses are gone," said Manning, the Trinidadian leader. "To see a building with a roof is a very rare sight."
Manning said Grenada's priorities are establishing security to end looting; recapturing prisoners; getting food, potable water, tents and blankets; restoring communications and electricity; and providing materials to rebuild.
More than 100 Caribbean soldiers from five countries arrived Thursday to help restore order on the island of 100,000.
On Friday, Trinidadian troops armed with assault rifles patrolled the marina and shopping area around St. George's Carenage and police Superintendent Edvin Martin reported only scattered looting.
The American Red Cross disaster unit, headed by Doug Allen, said Grenada's government has temporarily closed the country to relief shipments to get the security situation under control. Allen said they would send $70,000 worth of relief equipment as soon as they were allowed.
He said the country needs to get relief by Saturday or Sunday before things get critical.
An officer of Grenada's elite Special Service Unit said several guns were stolen from their station after officers abandoned it in the storm. He spoke on condition of anonymity.
As many as 75 convicts remain at large, acting prison superintendent Wesley Beggs said, after about 150 of the prison's 325 inmates escaped when the storm damaged the prison.
Troops from Barbados and Trinidad guarded Grenada's airport, where dozens of American medical students waited for chartered flights home.
"Nothing is going to be functioning here for a long time," said Olivier de Raet, 37, a medical student from Potomac, Maryland.
At St. George's University, student leader Salman Kahn, a 25-year-old from Chicago, was carrying a list of students and said about 270 had left on charter flights. Administrators said nearly 1,000 more were hoping to leave. The dean of students, C.V. Rao, said they were expecting the U.S. State Department to arrange flights for American citizens and that other charter flights were being arranged for students of other nationalities.
Manisha Sharma, a 31-year-old student from Boston, has been sleeping in a tent since her landlord's home was flattened. "I'm living in a tent, it's been fun," she said. "I have 15 people with me, four kids."
Grenada's Police Commissioner Fitzroy Bedeau said efforts to determine a death toll were hindered by blocked roads, landslides and lack of telephone service. Hospital director Esther Henry Fleary said at least 26 people have died, including the 8 year-old boy. She said the hospital had treated more than 500 injured people.
Ivan has also killed five people in Venezuela, one in Tobago, one in Barbados, and four youngsters in the Dominican Republic.