A strengthening Hurricane Matthew is steaming towards Florida with winds of 140mph as hundreds of thousands of people board up their homes and flee inland to escape the most powerful storm to threaten the Atlantic coast in more than a decade.
Florida governor Rick Scott urged the 1.5 million people living in evacuation zones in his state, its skies already darkening from the deadly storm's outer bands of rain, to "get out".
Speaking in Stuart on the Atlantic coast, he said anyone living in low-lying areas or on barrier islands must "evacuate, evacuate, evacuate".
Warning that "this is game day", Mr Scott warned people to stay away from the coast, adding: "No-one needs to be on the beach doing anything."
The hurricane has picked up strength as it closes in on the US, growing from a category three to a category four storm.
It has barrelled over the Bahamas and is now expected to scrape nearly the entire length of Florida's Atlantic coast from Thursday evening local time.
From there, forecasters said, it could push its way just off the coasts of Georgia and South Carolina before veering off to sea.
About two million people in Florida, Georgia and South Carolina have been warned to head inland, with nearly all of Florida's Atlantic coast and Georgia's entire coast under hurricane warnings.
Forecasters said the storm could dump up to 15in of rain in some areas and cause a storm surge of 5ft-8ft.
"This is a dangerous storm," Mr Scott warned. "The storm has already killed people. We should expect the same impact in Florida."
Major theme parks in inland Orlando remain open, but Walt Disney World and Universal Studios have cancelled Halloween events planned for Thursday night.
Fort Lauderdale Airport has closed to all flights.
Georgia governor Nathan Deal has ordered mandatory evacuations along the state's entire coast, the first such move in 17 years.
Mr Deal said everyone east of Interstate 95 should flee Georgia's six coastal counties - Chatham, Bryan, Liberty, McIntosh, Glynn and Camden. Those counties have a combined population of more than 522,000 people.
In South Carolina, governor Nikki Haley warned everyone in evacuation zones not to take the orders lightly. She said the surge from the storm could be as high as 8ft and affect not only the coast but also areas farther inland.
The state has reversed the eastbound lanes of Interstate 26 from Charleston to Columbia, allowing more motorists to move inland at once.