Hurricane Ike bore down on Cuba after roaring across low-lying islands Sunday, tearing apart houses, wiping out crops and worsening floods in Haiti that have already killed more than 300 people.

With Ike forecast to sweep across Cuba and possibly hit Havana head-on, hundreds of thousands of Cubans evacuated to shelters or higher ground. To the north, residents of the Florida Keys fled up a narrow highway, fearful that the "extremely dangerous" hurricane could hit them Tuesday.

At least 48 people died as Ike's winds and rain swept Haiti Sunday, raising the nation's death toll from four tropical storms in less than a month to 306. A Dominican man was crushed by a falling tree. It was too early to know of deaths on other islands where the most powerful winds were still blowing.

Ike's center hit the Bahamas' Great Inagua island, where the roofs of its two shelters both sprung leaks under the 135 mph (217 kph) winds. As the storm passed, people inside peeked through windows at toppled trees and houses stripped of their roofs.

"It's nasty. I can't remember getting hit like this," reserve police officer Henry Nixon said from inside a shelter holding about 85 people.

Great Inagua has about 1,000 people and about 50,000 West Indian flamingos _ the world's largest breeding colony. Both populations sought safety from the winds and driving rain, with the pink flamingos gathering in mangrove thickets. Biologists worried that their unique habitat could be destroyed.

"There's a possibility that the habitat can't really be replaced, and that they can't find an equivalent spot," said Greg Butcher, bird conservation director for the National Audubon Society. "You might have a significant drop in the number of flamingos."

At 8 p.m. EDT (0000 GMT), Ike had weakened slightly to a Category 3 hurricane with top winds of 120 mph (195 kph). It was about 30 miles off Cuba's northern coast, moving westward at 14 mph (22 kph).

The U.S. National Hurricane Center predicted Ike's eye would make landfall early Monday and could hit Havana, the capital of 2 million people with many vulnerable old buildings, by Monday night.

An informal tally of figures being released sporadically by individual provinces indicated that more than 600,000 people had been evacuated in eastern Cuba by Sunday evening. Former President Fidel Castro released a written statement calling on Cubans to heed security measures to ensure no one dies when Ike hits.

Cuba's government said more than 224,000 people were being evacuated in the central-eastern province of Camaguey alone. Foreign tourists were pulled out from vulnerable beach resorts, workers rushed to protect coffee plants and other crops, and plans were under way to distribute food and cooking oil to disaster areas.

"There's no fear here, but one has to prepared. It could hit us pretty hard," said Ramon Olivera, gassing up his motorcycle in Camaguey, where municipal workers boarded up banks and restaurants.

More than 100 people waited in chaotic bread lines at each of the numerous government bakeries around town as families hoarded supplies before the storm.

On the provincial capital's outskirts, trucks and dented school buses brought about 1,000 evacuees _ many of them families with small children _ to the sprawling campus of an art school.

Classrooms at the three-story school built on stilts were filled with metal bunk beds. The approaching hurricane brought a stiff breeze through the open windows.

Mirtha Perez, a 65-year-old retiree, said hardly anyone was left in her small town of Salome, located nearby.

"It's a huge evacuation," she said. "We are waiting and asking God to protect us and that nothing happens to us."

The first islands to bear Ike's fury Sunday were the Turks and Caicos, which have little natural protection from storm surges of up to 18 feet (5.5 meters).

The British territory's Premier Michael Misick said more than 80 percent of the homes were damaged on two islands and people who didn't take refuge in shelters were cowering in closets and under stairwells, "just holding on for life."

"They got hit really, really bad," Misick said. "A lot of people have lost their houses, and we will have to see what we can do to accommodate them."

In South Caicos, a fishing-dependent island of 1,500 people, most homes were damaged, the airport was under water, power will be out for weeks, and at least 20 boats were swept away despite being towed ashore for safety, Minister of Natural Resources Piper Hanchell said.

Tourism chairman Wayne Garland was text-messaging with two people in Grand Turk during the height of the storm. "They were literally in their bathroom because their roofs were gone," he said. "Eventually they were rescued."

Twenty-one of the Haitian victims, still unclaimed, were stacked in a mud-caked pile in a funeral home in the coastal Haitian town of Cabaret _ including two pregnant women, one with a dead girl still in her arms. More than a dozen children were in the pile. The rest of the known deaths were all in the Cabaret area, civil protection director Marie-Alta Jean Baptiste said.

Many more Haitian lives were threatened as Ike's downpours topped flooding from Hanna, Gustav and Fay. Officials said they would have to open an overflowing dam, inundating more homes and possibly causing lasting damage to key farming areas.

Heavy rains also pelted the Dominican Republic, Haiti's neighbor on the island of Hispaniola, where about 4,000 people were evacuated from northern coastal towns. One man was crushed by a falling tree.