SANTO DOMINGO, Dominican Republic (AP) -- French, British and Dutch rescuers struggled to rush aid to a string of Caribbean islands Thursday after Hurricane Irma left at least six dead and thousands homeless as it traced a course that could lead to a catastrophic strike on Florida over the weekend.
A swath of South Florida -- including much of the Miami metropolitan area of 6 million people -- was placed under a hurricane watch, with forecasters saying Irma could punish the entire Atlantic coast of the state and rage on into Georgia and South Carolina.
Officials imposed mandatory evacuation orders for parts of the Miami metro area and the Florida Keys as the fearsome Category 5 storm closed in with winds of 175 mph (281 kph).
By early Thursday afternoon, the hurricane was north of the Dominican Republic, where authorities reported some flooding and the evacuation of several thousand locals and tourists but no serious damage or casualties.
Skies over the Haitian capital, Port-au-Prince, were still clear just after noon local time. About a million people were without power in Puerto Rico after Irma sideswiped the island, but there were no immediate reports of large-scale casualties.
But the first islands hit by the storm were scenes of terrible destruction.
French Prime Minister Edouard Philippe said four people were confirmed dead and about 50 injured on the island of St. Martin, which is split between Dutch and French control. Officials said the toll could rise because rescue teams had yet to get a complete look at the damage. The French island of St. Barts also got slammed.
Two more deaths were reported on the British island of Anguilla and independent Barbuda.
French Interior Minister Gerard Collomb said 100,000 food rations were sent to St. Barts and St. Martin, the equivalent of four days of supplies.
"It's a tragedy, we'll need to rebuild both islands," he said. "Most of the schools have been destroyed."
Photos and video of St. Martin circulating on social media showed major damage to the Philipsburg airport and heavy flooding in the coastal village of Marigot. On St. Barts, Irma ripped off roofs and knocked out electricity.
Dutch Prime Minister Mark Rutte said the storm "caused wide-scale destruction of infrastructure, houses and businesses."
"There is no power, no gasoline, no running water. Houses are under water, cars are floating through the streets, inhabitants are sitting in the dark, in ruined houses and are cut off from the outside world," he said.
Irma, the most potent Atlantic Ocean hurricane ever recorded, appeared increasingly likely to rip into heavily populated South Florida early Sunday.
"This could easily be the most costly storm in U.S. history, which is saying a lot considering what just happened two weeks ago," said Brian McNoldy, a hurricane researcher at the University of Miami, alluding to the damage caused by Hurricane Harvey.
French President Emmanuel Macron's office said he would go to the islands as soon as the weather permits it. Saying he was "grief-stricken," Macron called for concerted efforts to tackle global warming to prevent similar natural disasters.
A Dutch navy ship arrived in St. Martin and was attempting to moor in the harbor and unload vital supplies. Another navy vessel was assessing damage with an onboard helicopter.
Two Dutch military aircraft were being sent the island of Curacao and on to St. Martin to deliver food and water intended to last the population of 40,000 five days. The aircraft were carrying 100 extra troops to deliver aid, repair infrastructure and restore order.
Britain was sending hundreds of troops and the Royal Navy flagship HMS Ocean to Anguilla, Montserrat and the British Virgin Islands.
In Anguilla, officials reported extensive damage to the airport, hospitals, shelters and schools and said 90 percent of roads were impassable.
On Barbuda, nearly every building was damaged when the hurricane's core crossed almost directly over the island early Wednesday. About 60 percent of its roughly 1,400 residents were left homeless, Antigua and Barbuda Prime Minister Gaston Browne told The Associated Press.
"It is just really a horrendous situation," Browne said.
He said roads and telecommunications systems were wrecked and recovery would take months, if not years. A 2-year-old child was killed as a family tried to escape a damaged home during the storm, Browne said.
On St. Thomas in the nearby U.S. Virgin Islands, Laura Strickling spent 12 hours hunkered down with her husband and 1-year-old daughter in a boarded-up basement apartment with no power as the storm raged outside. They emerged to find the lush island in tatters. Many of their neighbors' homes were damaged and once-dense vegetation was largely gone.
"There are no leaves. It is crazy. One of the things we loved about St. Thomas is that it was so green. And it's gone," Strickling said. "It will take years for this community to get back on its feet."
More than half the island of Puerto Rico was without power, leaving more 900,000 in the dark and nearly 50,000 without water, the U.S. territory's emergency management agency said in the midst of the storm. Fourteen hospitals were using generators after losing power, and trees and light poles were strewn across roads.
Puerto Rico's public power company warned before the storm hit that some areas could be left without power from four to six months because its staff has been reduced and its infrastructure weakened by the island's financial crisis.
President Donald Trump approved an emergency declaration for the U.S. Virgin Islands and Puerto Rico, allowing the Federal Emergency Management Agency and other agencies to remove debris and provide other aid.
The U.S. National Hurricane Center predicted Irma would remain at Category 4 or 5 as it passed just to the north of the Dominican Republic and Haiti, neared the Turks & Caicos and parts of the Bahamas by Thursday night and skirted Cuba on Friday night into Saturday.
In Florida, people rushed to board up their homes and gas up their cars.