Powerful Hurricane Ike rolled down an uncertain path Sunday that may lead to the U.S. Gulf Coast late this week, forcing emergency officials to pay attention and leaving millions of people from Florida to Mexico to wonder where it will eventually strike.

Officials in the Florida Keys planned to start a phased evacuation for residents Sunday morning after telling visitors a day earlier to get out. Ike, a dangerous Category 4 storm with winds early Sunday of near 135 mph, was forecast to affect the Keys starting Monday night on a potential track for the central Gulf.

Ike roared across the low-lying Turks and Caicos island chain before dawn Sunday as people in the British territory sought refuge in emergency shelters or in their homes.

Click here for photos.

Click for tracking maps and satellite images at MyFOXHurricane.com.

At 5 a.m. EDT, the National Hurricane Center in Miami said Ike's eye was about 65 miles east of Great Inagua Island in the Bahamas. It was moving west about 15 mph on a path that would take it near or over eastern Cuba Sunday night and central Cuba late Monday.

"These storms have a mind of their own," Florida Gov. Charlie Crist said after a meeting Saturday with mayors and emergency officials. "There are no rules, so what we have to do is be prepared, be smart, vigilant and alert."

In Haiti, authorities tried to move thousands of people into shelters ahead of Ike while still struggling to recover from a drenching from Tropical Storm Hanna. Rescue workers feared Hanna's death toll could rise into the hundreds in the flooded city of Gonaives if Ike dumped more rain from outer storm bands as the storm rumbled nearby.

In Louisiana, still recovering from last week's Hurricane Gustav, Gov. Bobby Jindal set up a task force to prepare for the possibility of more havoc.

"We're not hoping for another strike, another storm, but we're ready," he said.

Even as Gustav evacuees headed home, New Orleans Mayor Ray Nagin said officials were anxiously monitoring Ike on a projected path toward the Gulf.

"Our citizens are weary and they're tired and they have spent a lot of money evacuating ... from Gustav," he said. He added that if Ike were to threaten, "my expectations this time is, it will be very difficult to move the kind of numbers out of this city that we moved during Gustav."

The storm had sustained winds of near 135 mph and even stronger gusts after muscling up from a Category 3 to a Category 4 storm Saturday. It was moving nearly due west at about 15 mph and expected to turn slightly toward the northwest Monday.

"It's a very dangerous storm," hurricane center meteorologist Colin McAdie told The Associated Press. "There's going to be some ups and downs, but we expect it to remain a major hurricane over the next couple days."

The hurricane center said Ike was generating large swells at sea that could generate life-threatening rip currents along portions of coast in the southeastern U.S.

Tourists were urged to leave the Bahamas, and authorities in the Dominican Republic began evacuating dozens of families from river banks that could flood because of two already overfilled dams.

Click for more from the National Hurricane Center.