US Florida Keys are being evacuated and the state is preparing for the possibility of a third hurricane in a month as Hurricane Ivan continues churning Thursday in the Caribbean, leaving a path of destruction unmatched there in at least a decade.

At 11 a.m. Thursday, Ivan's center was 430 miles east-southeast of Kingston, Jamaica, or about 960 miles southeast of Miami. It had 160 mph wind and was moving about 15 mph. National Hurricane Center forecasters predict that Ivan could hit the Florida Keys as a Category 4 hurricane, with wind of 131 to 155 mph, late Sunday or early Monday.

"I don't think that people will think twice when we tell them it's a Four heading right at us. I think they will be pretty responsive," Monroe County, Fla. emergency manager Irene Toner said of evacuation efforts.

Monroe County emergency officials asked tourists to leave the Keys at 9 a.m. Thursday, the third visitor evacuation there in a month, following Charley and Frances. Mobile home residents were urged to begin evacuating at 6 p.m. Thursday, and other residents were told to prepare to leave Friday.

Jim Lushine, a National Weather Service meteorologist in Miami, said Ivan could make history.

"We could have three of the most intense storms to ever hit Florida in one season that we know about, anyway," Lushine said. Remnants of Hurricane Frances, which pushed north into Georgia and beyond after striking Florida on Sunday, still are drenching much of the East Coast. The storm is blamed for 19 deaths in Florida, Georgia and South Carolina. It also killed two in the Bahamas.

Ivan's deadly force turned concrete houses into rubble in the southern Caribbean on Wednesday as the storm headed toward the USA. (Related video and story: Ivan leaves death in its wake| Ivan smashes islands)

The National Hurricane Center charts the storm on a track similar to that of Hurricane Charley, which hit southwest Florida with 145-mph winds last month. Charley killed 27 people in Florida and caused at least $6.8 billion in insured damage.

But Ivan would have to take a sharper turn north than its present path to become the third hurricane to strike Florida in a month.

Ivan is expected to hit Cuba on Saturday, after which the path of the storm "is highly uncertain," according to the hurricane center. But forecasters caution that one possible scenario shows Ivan approaching Punta Gorda, Fla., one of the areas hardest hit by Charley.

Some computer weather models predict a path over Florida, while others suggest the storm might head out to sea. "There is no apparent reason to favor one scenario over the other," the center reported Wednesday.

President Bush, who signed a $2 billion emergency relief bill for Florida on Wednesday morning, flew to the state in the afternoon for his third hurricane-related visit since mid-August. Bush went to Port St. Lucie to survey damage from Frances and help distribute aid with his brother Jeb, Florida's governor. From there, he went to the hurricane center in Miami for an update on Ivan.

Source: Agencies