Florida Braces For Worst Scenario

With ferocious winds that riled up monstrous waves, Hurricane Ivan bore down on Jamaica on Thursday, leaving a devastated Grenada in its wake and creating panic in its projected path. Foreigners began fleeing Jamaica and U.S. officials ordered people to evacuate the Florida Keys.

Ivan weakened slightly and was downgraded Thursday from a Category 5 hurricane -- the most powerful -- to a Category 4 storm packing 150 mph winds but was still expected to pound Jamaica, where officials urged a half million people to evacuate coastal and flood-prone areas, on Friday.

U.S. officials also were considering evacuating the 1,000 U.S. citizens in Grenada, most university students who said they want to leave.

Officials told tourists and residents to evacuate the Florida Keys because Ivan could hit the island chain by Sunday. It was the third evacuation ordered there in a month, following Hurricane Charley and hard on the heels of Hurricane Frances.

Forecasters told CBS News Correspondent Lee Cowan Florida isn't unlucky, it's just long overdue, and things are only going to get more active.

"We should continue to see more hurricanes and stronger hurricanes for the next 10, to 30, to 40 years," said Max Mayfield of the National Hurricane Center.

But for the moment, it's where Ivan is going next that is the real worry. Current forecasts have it heading right over the same areas as both Charley and Frances hit.

The deadliest storm to hit the Caribbean in a decade has killed 23 people in five countries since Tuesday.

On Thursday, though it was nearly 200 miles from land, it killed four youngsters Thursday in Santo Domingo, capital of the Dominican Republic.

In St. George's, Grenada's capital, police fired tear gas to try to stop a looting frenzy. Hundreds of people, including entire families with children, smashed hurricane shutters and shop windows to heft away televisions and shopping carts of food.

Caribbean troops were on the way to help restore order.

Thursday afternoon, police set up barricades on roads leading into the capital and ordered all but emergency personnel off the streets. Hundreds of screaming and shoving people said they had to get to town to buy water and food. Police fired tear gas.

But many managed to get through, saying they were desperate for water.

Among them was Dawn Brown, a 30-year-old housewife, who said she and her children ran from room to room in her home as Ivan ripped off sections of their roof when it hit Tuesday. Eventually, the house was left roofless and the family hid beneath a mattress as its 130-mph winds howled around them.

"I stared death in its face. What could be more scary than that?" Brown said as she wandered the streets in search of water. The island has had no running water since Monday, when officials turned it off to save the plant from damage.

Hurricane Ivan ripped up nearly every utility pole, leaving residents without electricity and landline telephone service.

The first shipment of emergency relief arrived Thursday from the United States, which declared Grenada a disaster area to allow the immediate release of $50,000. There were enough blankets, plastic sheeting, dry food and water for 20,000 people, according to the U.S. Embassy in Barbados.

Military officials in Barbados said 60 soldiers were on the way to Grenada — 30 from Barbados, 15 from St. Kitts and 15 from Antigua. Dominica's Prime Minister Roosevelt Skerrit said he was sending 17 police officers on Friday.

In Jamaica on Wednesday, Prime Minister P.J. Patterson urged the island's 2.6 million people to pray and "prepare for the worst scenario." On Thursday, he put security forces on high alert and told residents in flood-prone areas to be ready to evacuate.

Hundreds of tourists packed the airport of Montego Bay resort.

At the airport of Kingston, the capital, dozens of foreigners lined up for tickets.

"We were going to stick it out but the company I work for told everybody to evacuate," said Dennis Hennessey, 39, a building contractor from Essex Junction, Vermont, who was helping build the new U.S. Embassy in Kingston.

"They say Jamaica is a blessed place, and I hope it is," he said.

In Grenada, U.S. officials were assessing the airport and security to determine whether an evacuation of U.S. citizens is possible and necessary, the U.S. Embassy in Barbados said.

In Jamaica, workers began bolting plywood boards to windows and most businesses closed early.

Grocery stores and gas stations stayed open for long lines of people stocking up against the storm.

In the seaside town of Port Royal, just outside Kingston, fishermen pulled wooden skiffs ashore as menacing storm clouds rolled in. The town of squat concrete homes and zinc roofs was nearly wiped out by Hurricane Charley in 1951.

"It's Ivan the Terrible," said fisherman Peter Kission, 47. "We've been through this before. We can take another."

But 50-year-old Port Royal native Gabby Bess wasn't so sure. "If it hits us like Gilbert did, we'll be in a whole heap of trouble."

Hurricane Gilbert was only a Category 3 storm when it devastated Jamaica in 1988.

Ivan's outer bands hit Barbados' south coast on Tuesday, damaging some 220 homes and killing a Canadian woman who was searching for her cat. It also tore roofs from dozens of homes in St. Lucia and in Tobago, where another woman died. Its heavy rains flooded parts of Venezuela's coast and left four Venezuelans dead.

In Grenada, it killed 13 people and British sailors were treating about 100 injured at the hospital, where they restored generator power Thursday.

"We were saving lives yesterday," said Royal Navy Commander Mike McCartain.

The British patrol boat HMS Richmond and a supply ship rushed to Grenada on Wednesday and provided communications for Prime Minister Keith Mitchell to tell his people and the world what a disaster had hit.

Sailors on Thursday said they had cleared the damaged and flooded airport runway for emergency flights.

Ivan damaged 90 percent of homes in Grenada, according to Mitchell, whose own home was flattened.

Jamaica posted a hurricane warning Thursday. Haiti's southwest remained on hurricane watch. Dominican Republic's Barahona peninsula was under hurricane watch and the southwest coast a tropical storm warning. Cayman Islands posted a hurricane watch as did Cuba for central and eastern parts of the island.

CBS News State Department Charlie Wolfson reports the State Department is expected to announce that the U.S.-interest section in Havana will be affected by Ivan.

Ivan's outer bands brought drenching rain to Haiti's southwest peninsula overnight, where residents of sea-level Les Cayes town worried it would bring disaster equal to May floods that killed 1,700 people and left 1,600 missing and presumed dead along the Haiti-Dominican Republic border.

The storm is projected to pass directly over Jamaica on Friday, then across Cuba and into the heart of the hurricane-weary southern United States.