PUNTA GORDA: Hurricane Ian plunged much of coastal southwest Florida into darkness Wednesday, as the monster storm brought "catastrophic" storm surges, wind and flooding that had officials readying a huge emergency response.
The US Border Patrol said 20 migrants were missing after their boat sank, with four Cubans swimming to shore in the Florida Keys islands and three rescued at sea by the coast guard.
The National Hurricane Center (NHC) said the eye of the "extremely dangerous" hurricane made landfall just after 3:00 pm (1900 GMT) on the barrier island of Cayo Costa, west of the city of Fort Myers.
Dramatic television footage from the coastal city of Naples showed floodwaters surging into beachfront homes, submerging roads and sweeping away vehicles.
Some neighbourhoods in Fort Myers, which has a population of more than 80,000, resembled lakes.
The NHC said Ian was packing maximum sustained winds of 150 miles (240 kilometres) per hour when it landed.
It later weakened to a Category 1 hurricane with winds of 90 miles per hour, while still battering Florida with "storm surge, winds and flooding," the NHC said at around 11:00 pm local time Wednesday (0300 GMT).
More than two million customers were without electricity in Florida on Wednesday evening, out of a total of more than 11 million, with southwestern areas of the state the hardest hit, according to the PowerOutage.us tracking website.
Ian is set to affect several million people across Florida and in the southeastern states of Georgia and South Carolina.
As hurricane conditions spread, forecasters warned of a once-in-a-generation calamity.
"This is going to be a storm we talk about for many years to come," said National Weather Service director Ken Graham. "It's a historic event."
Florida's Governor Ron DeSantis said the state was going to experience a "nasty, nasty day, two days."
The town of Punta Gorda, north of Fort Myers, was in near-total darkness as the storm wiped out power, save for the lucky few buildings with generators.
Howling winds ripped branches off trees and pulled chunks out of roofs.
About 2.5 million people were under mandatory evacuation orders in a dozen coastal Florida counties, with several dozen shelters set up, and voluntary evacuation recommended in others.
For those who decided to ride out the storm, authorities stressed it was too late to flee and residents should hunker down and stay indoors.
Airports in Tampa and Orlando stopped all commercial flights, and cruise ship companies delayed departures or cancelled voyages.
With up to 30 inches (76 centimetres) of rain expected to fall on parts of the so-called Sunshine State, and a storm surge that could reach devastating levels of 12 to 18 feet (3.6 to 5.5 meters), authorities were warning of dire emergency conditions.
"This is a life-threatening situation," the NHC warned.
The storm was set to move across central Florida before emerging in the Atlantic Ocean by late Thursday.
'Nothing is left here'
Ian had plunged all of Cuba into darkness a day earlier, after battering the country's west as a Category 3 storm and downing the island's power network.
"Desolation and destruction. These are terrifying hours. Nothing is left here," a 70-year-old resident of the western city of Pinar del Rio was quoted as saying in a social media post by his journalist son, Lazaro Manuel Alonso.
At least two people died in Pinar del Rio province, Cuban state media reported.
In the United States, the Pentagon said 3,200 national guard personnel were called up in Florida, with another 1,800 on the way.
DeSantis said state and federal responders were assigning thousands of personnel to address the storm response.
"There will be thousands of Floridians who will need help rebuilding," he said.
As climate change warms the ocean's surface, the number of powerful tropical storms, or cyclones, with stronger winds and more precipitation is likely to increase.
The total number of cyclones, however, may not.
According to Gary Lackmann, a professor of atmospheric science at North Carolina State University, studies have also detected a potential link between climate change and rapid intensification -- when a relatively weak tropical storm surges to a Category 3 hurricane or higher in a 24-hour period, as happened with Ian.
"There remains a consensus that there will be fewer storms, but that the strongest will get stronger," Lackmann told AFP.