Hurricane Irma remains a Category 4 storm as of the National Hurricane Center's 8 a.m. advisory and the storm continues to move on a west-northwest track.
The storm barreled between southeastern Cuba and the Turks and Caicos Islands early Friday morning and is expected to move westward toward central Cuba and the Bahamas.
At least 10 people were killed as Irma pummeled small northeastern Caribbean islands such as Barbuda and St. Martin/St. Maarten. In Puerto Rico, hundreds of thousands of people were left without power.
Irma was downgraded to an "extremely dangerous" category 4 storm on Friday, with winds reaching a sustained maximum of 150 mph, the US National Hurricane Center said. At its peak, winds reached sustained maximums of 180 mph.
"Some fluctuations in intensity are likely during the next day or two, but Irma is forecast to remain a powerful category 4 hurricane as it approaches Florida," the advisory said.
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Here are the latest developments
-- Irma is forecast to move toward the southeastern Bahamas Friday morning, then heading between the north coast of Cuba and the Bahamas in the next day or two.
-- Hurricane warnings are in effect for parts of Cuba, Haiti, the Turks and Caicos Islands, and the southeastern, central and northwestern Bahamas.
-- The Red Cross said as many as 26 million people could be exposed to destructive winds and torrential rain just in the Dominican Republic, Haiti and Cuba.
-- Hurricane and storm surge warnings are also in effect for South Florida, extending from Jupiter Inlet on the east coast of the state, southward around the Florida Peninsula to Bonita Beach on the west coast. The hurricane warning included the Florida Keys, Lake Okeechobee and Florida Bay.
-- Both the French and Dutch portions of the island of St. Martin are suffering looting in the wake of Irma, authorities said.
The Bahamas, a nation of about 390,000, ordered evacuations ahead of Irma's arrival for six southern islands -- Mayaguana, Inagua, Crooked Island, Acklins, Long Cay and Ragged Island.
"This is the largest such evacuation in the history of the country," Prime Minister Hubert Minnis said.
Tourists and hundreds of thousands of residents have also been evacuated from parts of Cuba. Hotels on the northern coast that would normally be busy at this time of year were empty Friday, CNN's Patrick Oppmann reported from Caibarien.
Some residents have been evacuated to bomb shelters built during the Cuban missile crisis of the 1960s.
Devastation to islands
Irma, which at its peak sustained maximum wind speeds of 185 mph or above for longer than any storm ever recorded in the Atlantic basin, brought heavy rain and powerful winds overnight to the low-lying Turks and Caicos Islands.
Residents of the islands, a British overseas territory with a population of about 35,000, were told to stay put.
"Fifteen roofs have come off and there's damage to part of the roof of the hospital," Gov. John Freeman told CNN on Thursday night. He said there was "quite a bit of damage" on the capital island of Grand Turk.
The UK Foreign Office said officials on the islands were working intensively on disaster preparedness and response.
"Some of these Turks and Caicos (Islands) will be completely overwashed," CNN meteorologist Chad Myers said.
In Puerto Rico, about 56,680 customers were without water, with the island's northeast hit the hardest, according to Jesus Poupart of the emergency operations center.
In the beachside area of Piñones near San Juan, Irma tore the roof off Cristian López's fried-food restaurant. He said he wouldn't be able to reopen the place for about five days.
"At least we are all alive," he said.
Irma is expected to bring massive rainfall, which could cause flash floods and mudslides in parts of Puerto Rico, the Virgin Islands, Dominican Republic, Haiti, Turks and Caicos islands, the Bahamas and Cuba, as well as the US.
After Irma, Hurricane Jose looms
The Caribbean islands already pummeled by Irma have begun assessing the damage, finding shredded buildings, battered cars and streets submerged in water.
Barbuda is barely habitable, with about 95% of its buildings damaged, Prime Minister Gaston Browne said late Wednesday.
Barbuda, which has 1,800 residents, is one of two major islands in the nation of Antigua and Barbuda. Browne estimated the damage will cost $100 million to fix.
"It looks like (a) garbage disposal," Marlon Carr, a photographer who toured the island with Browne, told CNN on Thursday. "There was rubble and roof galvanized all over the island. It looked like some of the houses ... were imploded on."
Witnesses told him of "40-foot containers flying, animals flying" during the storm, he said.
Irma's eye passed directly over Barbuda on Wednesday and now the northeastern Caribbean nation is anxiously watching Hurricane Jose to the east, which has strengthened to a Category 3 storm.
Antigua and Barbuda are under a hurricane watch for Jose, which could pass close to those islands Saturday. The government has called for voluntary evacuations from Barbuda, Browne said.
The island of St. Martin was also badly hit, with about 50 people reported injured as well as the four killed.
Dutch Prime Minister Mark Rutte said Friday that the looting situation in St. Maarten, the Dutch portion of St. Martin island, was "serious" in the wake of the hurricane, a spokesman for his office said.
Local authorities, in collaboration with the Dutch military, are restoring order on the island, the spokesman said.
The airport in St. Maarten is reopened for military use only, with military aircraft focused on bringing help and personnel to the island, he added.
France's overseas territories minister, Annick Girardin, also confirmed looting in the French portion of the island, St. Martin.
"Our worst fears have played out in Barbuda and elsewhere," said Walter Cotte, the regional director for the Americas for the Red Cross. "We can't yet assess the full extent of damage, but we expect that the Red Cross will be delivering extensive support to many thousands over the coming weeks and months."
Florida and the Southeast US brace for Irma
The National Hurricane Center warned Thursday that it had become more likely that Irma would "make landfall in southern Florida as a dangerous major hurricane, and bring life-threatening storm surge and wind impacts to much of the state."
It warned of possible storm surges that could bring five to 10 feet of water above ground on Florida's coast.
The hurricane center forecast moved the most likely path of the eye of the storm to the west, which means Miami could take a major hit.
"This storm has the potential to catastrophically devastate our state and you have to take this seriously," warned Florida Gov. Rick Scott.
Scott urged residents to be prepared regardless of which side of the coast they live in the state. "This is not a storm you can sit and wait through," he said.
Scott said others in Florida need to watch Irma's path and be ready to move to shelters for safety if necessary. Schools will be closed Friday.
Evacuees stocked up on supplies, waited for hours at gas stations, and sat through massive traffic jams on the interstate.
Monroe County Administrator Roman Gastesi told residents in the Florida Keys that they need to heed the evacuation order and leave.
Florida is not the only state preparing for possible impact. Some computer models show Irma potentially threatening Georgia and South Carolina.
Georgia's Gov. Nathan Deal declared a state of emergency for 30 counties and the state is ordering coastal evacuations for people in the Savannah area and everywhere along the coast east of Interstate 95, starting Saturday.