The first rain from Hurricane Dennis (search) started falling Friday on the Florida Keys as the storm barreled toward the Gulf of Mexico, and forecasters warned that it might score a direct hit on the island chain.

Dennis was packing 145 mph wind at early afternoon, making it a strong Category 4 storm. Even if the eye passes to the west of the Keys (search), forecasters warned, hurricane-force winds extended up to 50 miles from the center, and tropical storm-force winds stretched up to 160 miles out.

Click here to track Hurricane Dennis' path.

Key West's streets were calmer than usual Friday, the result of an evacuation order issued a day earlier. The storm could batter the islands by evening, forecasters said. Morning breezes were expected to grow into stronger winds, joined by up to 8 inches of rain and storm surges of up to 6 feet.

Utility workers were out Friday to trim trees away from power lines, but outages were expected before day's end, said Florida Keys Electric Co-op CEO Tim Planer (search). "The weather's deteriorating here pretty quickly," he said.

Dennis began to cross Cuba on Friday afternoon, and was described as "extremely dangerous" by the National Hurricane Center in Miami. Dennis was blamed for at least five deaths in Haiti.

After passing the Keys, the storm's arms could batter Florida's west coast before the center hits the U.S. mainland around late Sunday, somewhere between the Florida Panhandle and Louisiana.

An estimated 40,000 residents and tourists were ordered out of the beachside town of Gulf Shores, Ala., on Friday, and evacuation was also requested in a flood-prone parish south of New Orleans that is home to 458,000. Mississippi officials planned an announcement later in the day.

Inland-bound traffic along the coast was already growing heavy, and hotels were filling more than 150 miles to the north.

"All day long all of our phones have been ringing. The only thing we can tell people is that we are sold out," said Lasonya Lewis, a desk clerk at a Courtyard by Marriott in Montgomery, Ala.

In Florida, some gas stations had run out of fuel Friday, and cars lined up at those that still had supplies. State officials said fuel supplies and distribution were normal, and dry pumps would be restocked by Saturday.

A hurricane warning was issued for the lower Keys. A hurricane watch was in effect for the middle and upper Keys.

Gov. Jeb Bush declared a state of emergency and cut short a Maine vacation to return to Tallahassee. Everyone in the southernmost Keys, along with all tourists and mobile home residents in the low-lying island chain, were ordered to evacuate. People snatched up bottles of water and other hurricane supplies as cars streamed out of the Keys.

Airlines reported that nearly all flights out of Key West were full and Greyhound added buses to help get thousands of people out of the area.

"This is my wedding night, and I'll be on a bus," said Sue Theroux, 42, of Point Pleasant, N.J., as she and her groom, Tom Theroux, waited in Key West for a Greyhound late Thursday. The couple had planned to marry on Saturday but hastily moved up the ceremony after the evacuation order.

Some, including lifelong Key West resident Barbara Crespo, planned to remain.

"There's not a whole lot you can do when you live in paradise," the 49-year-old real estate agent said Friday as she rode bikes with her husband.

The Lower Keys Medical Center closed, and even emergencies were not treated. A sign outside the Conch Republic Liquors store read, "Dennis Don't Be a Menace."

At 2 p.m. EDT, Dennis' eye was at Cuba's southern coast, about 125 miles southeast of Havana, and about 190 miles south-southeast of Key West. It was wobbling slightly as it moved northwest at about 17 mph.

Dennis weakened slightly as it arrived in Cuba, but forecasters expect it to remain a major hurricane with winds of at least 111 mph when it enters the Gulf in the evening. It was unlikely to return to its most ferocious strength, however, because the sea water isn't warm enough yet, center meteorologist Chris Hennon said.

Forecasters expected a possible storm surge of up to 7 feet along the Florida's southwestern coast, and tornadoes could also form through Saturday in the state's southern section, including the Keys. The southwestern county of Collier issued a voluntary evacuation for people living in coastal areas and on barrier islands.

At Cape Canaveral, NASA decided Friday that Dennis would be far enough west to let the space shuttle Discovery stay on its launch pad, and the liftoff of the first shuttle mission since the Columbia disaster remained on track for Wednesday.

Many in Dennis' projected path already got a wake-up call this week from a surprising Tropical Storm Cindy, which caused three deaths, knocked out power to thousands, and spawned twisters that toppled trees and caused up to $40 million damage to the Atlanta Motor Speedway.

By midday Friday, the remnants of Cindy were centered on Maryland's eastern shore, moving toward New England. Flood and flash flood watches were posted from Georgia into New England.

Four hurricanes battered Florida last year, causing more than $40 billion in damage.