ST JOHN'S, ANTIGUA: After battering Cuba on Friday and leaving more than 20 dead across the Caribbean, newly strengthened Irma is taking aim at south Florida with 160 mph (257 kph) winds as another hurricane follows close behind.

Irma regained Category 5 status late Friday as thousands of people in the Caribbean fought desperately to find shelter or escape their storm-blasted islands and more than 6 million people in Florida and Georgia were warned to leave their homes.

Puerto Rico, the Dominican Republic and the eastern part of Cuba reported no major casualties or damage by mid-afternoon after Irma rolled north of the Caribbean's biggest islands.

Many residents and tourists were left reeling after the storm ravaged some of the world's most exclusive tropical playgrounds, known for their turquoise waters and lush green vegetation. Among them: St Martin, St Barts, St Thomas, Barbuda and Anguilla.

Irma smashed homes, shops, roads and schools; knocked out power, water and telephone service; trapped thousands of tourists; and stripped trees of their leaves, leaving an eerie, blasted-looking landscape littered with sheet metal and splintered lumber.

On Friday, looting and gunshots were reported on St Martin, and a curfew was imposed in the US Virgin Islands.

Many of Irma's victims fled their islands on ferries and fishing boats for fear of Hurricane Jose, a Category 4 storm with 150 mph winds that could punish some places all over again this weekend.

"I don't think it takes a rocket scientist to know that further damage is imminent," said Inspector Frankie Thomas of the Royal Police Force of Antigua and Barbuda.

On Barbuda, a coral island rising a mere 125 feet (38 meters) above sea level, authorities ordered an evacuation of all 1,400 people to neighboring Antigua.

The dead included 11 on St Martin and St Barts, four in the US Virgin Islands, four in the British Virgin Islands and one each on Anguilla and Barbuda.

Also, a 16-year-old junior professional surfer drowned Tuesday in Barbados while surfing large swells generated by an approaching Irma.

Many victims picked through the rubble of what had once been Caribbean dream getaway homes.

On St Thomas in the US Virgin Islands, power lines and towers were toppled, a water and sewage treatment plant was heavily damaged and the harbor was in ruins, along with hundreds of homes and dozens of businesses.

Opera singer Laura Strickling and her husband, Taylor, moved to St Thomas three years ago from Washington so he could take a job as a lawyer. They rented a top-floor apartment with a stunning view of the turquoise water of Megan's Bay.

Strickling huddled with her husband and their year-old daughter in a basement apartment along with another family as the storm raged for 12 hours.

"The noise was just deafening. It was so loud we thought the roof was gone," she said, adding that she and the three other adults "were terrified but keeping it together for the babies."

Strickling, who used to visit her husband in Afghanistan when he worked there, added: "I've had to sit through a Taliban gunfight, and this was scarier."

When they emerged, they found their apartment was unscathed and the trees had no leaves.

"We're obviously worried by the thought of having to do it all again with Hurricane Jose. It's a little, a little, well, it's not good," she said, her voice trailing off.

Irma threatened to push its way northward from one end of Florida to the other beginning Sunday morning in what many fear could be the long-dreaded, catastrophic Big One. Evacuees clogged interstates across Florida and Georgia, as far north as Atlanta.

Meanwhile, more than 1,000 miles (1,600 kilometers) to the east, authorities commandeered a ferry from Montserrat with room for 350 and began moving people from Barbuda to the larger island of Antigua. The owners of several fishing boats also volunteered to help.

Thomas, the royal police inspector, said few structures were left standing in Barbuda, and even those that were not destroyed had some damage.

On St Martin, which is divided between Dutch and French control, cafes and shops were swamped, and the storm left gnarled black branches denuded of leaves. Battered cars, corrugated metal, plywood, wrought iron and other debris covered street after street. Roofs were torn off numerous houses.

Little was left of St Martin's Hotel Mercure but its sign, painted on a still-standing wall.

William Marlin, prime minister of the Dutch side of St Martin, said recovery was expected to take months even before Jose threatened to make things worse.

"We've lost many, many homes. Schools have been destroyed," he said. "We foresee a loss of the tourist season because of the damage that was done to hotel properties, the negative publicity that one would have that it's better to go somewhere else because it's destroyed. So that will have a serious impact on our economy."

Jalon Shortte said riding out Irma in his top-floor apartment on Tortola, in the British Virgin Islands, was the scariest thing he has ever been through.

The air pressure hurt his ears, trees fell on his roof, windows blew out and a door came off, he wrote on Facebook. The storm even took paint off the walls, he said.

His Facebook page was filled with images he took from around Tortola of sunken yachts, crushed vehicles and mounds of debris. He said looting was rampant.

Amid the devastation, Shortte worked to bring a water desalination plant online.

"We have to stick together and rebuild," he said.