People in the Florida Keys were ordered to flee and residents along hundreds of miles of Gulf Coast began boarding up Thursday as Hurricane Dennis (search) took aim at the the storm-weary region.

Forecasters warned residents from Florida to Louisiana that Dennis could be a major hurricane with top winds of 130 mph by the time it hits this weekend. But many in the projected path already got their wake-up call this week from a surprising Tropical Storm Cindy (search) that caused three deaths, knocked out power to thousands, and spawned twisters that toppled trees and caused up to $40 million damage to a famed NASCAR track.

"We're trying to get ready for whatever happens. We've been through so much already," Joe Hendrickson said as he painted a house in Punta Gorda, where blue tarps still dot the rooftops of homes waiting to be repaired from Hurricane Charley (search), the first of a record four hurricanes to hit Florida last year.

"They're freaked out," Jose Davila said of residents he encountered snapping up plywood and storm shutters at a Home Depot in nearby Port Charlotte. "They're taking it serious. They've seen what a hurricane can do."

Tourists throughout the Florida Keys (search) were ordered to evacuate, as were all mobile home residents — and all southernmost residents of the island chain.

A hurricane warning was issued for the lower Florida Keys, and forecasters said the storm could begin lashing the area with strong wind and rain by late Friday.

Lines of cars were seen streaming out of the island chain Thursday. Airlines reported that nearly all flights out of Key West were full, and Greyhound added buses to help get residents out of the area.

Dennis was forecast to be between the tip of Mexico's Yucatan Peninsula and Florida's southern tip by Saturday morning. At 5 p.m. EDT, Dennis' center was about 520 miles south-southeast of Miami. It was moving northwest at 15 mph and its winds had strengthened to 115 mph, making it a Category 3, a major hurricane with winds from 111 mph to 130 mph.

In Gulf Shores, Ala., residents still haven't fully rebuilt the damage from Hurricane Ivan 10 months ago. Only about 60 percent of rental properties have reopened, with damaged roofs and empty buildings still spotting the beachfront.

"I'm worried about flying trash cans and two-by-fours," said Nick Primozic, among the lucky ones who bought plywood at a home improvement store before it sold out.

In Louisiana, preparations for Dennis were delayed by the aftermath of Cindy, which caught many by surprise when it moved ashore Tuesday night with 8 inches of rain and 70-mph winds that knocked out power to about 287,000 customers, the largest blackout since Hurricane Betsy 40 years ago.

An estimated 100,000 customers were still without power Thursday, forcing many people — especially the sick, elderly and families with infants — to buy generators or evacuate to hotels to make it through another hot and sticky day.

In Leeville, along Louisiana's marshy coast, fishing boats were dashed against a bridge, roofs were torn off buildings, and at least one collapsed — a scene that caused some to suggest Cindy packed the punch of a Category 1 hurricane.

Cindy's remnants dumped up to 4 inches of rain Thursday on mountainous regions of western North and South Carolina.

Two deaths were blamed on Cindy in Georgia, where the remnants dumped up to 5 inches of rain and caused damages estimated at $75 million statewide.

In Hampton, south of Atlanta, a suspected F-2 tornado — packing winds of 113 to 157 mph — blew off roofs and popped out windows to luxury boxes at Atlanta Motor Speedway, causing damage estimated at $25 million to $40 million.

"Everything but the track surface has suffered some kind of damage," said track president Steve Clark. "We don't know to what extent yet, but it's major. There are some buildings that will have to be torn down."

Melony Duffey stood in her yard in nearby McDonough and surveyed the wreckage of eight toppled pine trees that destroyed her family's GMC Suburban and a van.

"I've never been through anything like this before and I've been in Georgia all my life," she said. "Houses on the street behind us, they have trees inside their houses. It's like every other house."