 "A man stands next to a destroyed house after Hurricane Matthew passes Jeremie, Haiti. (Photo: Reuters)")
Some 3 million people on the US southeast coast faced urgent evacuation as monstrous Hurricane Matthew -- now blamed for more than 250 deaths in Haiti alone -- bore down for a direct hit on Florida.
Highways in Florida and neighboring states clogged up with people streaming inland to escape the storm.
President Barack Obama on Thursday declared a federal state of emergency in Florida as it braced for the ferocious Category Four hurricane.
Poor and vulnerable Haiti remained essentially cut in half two days after Matthew hit. Interior Minister Francois Anick Joseph said at least 108 Haitians have died, with 50 killed in a single town and reports of "complete destruction" in the island's south.
In its latest target, the storm slammed the Bahamas on Thursday.
According to the forecast track, the hurricane could make landfall on Friday in the United States near Cape Canaveral, where NASA's Kennedy Space Center is located.
As US gas stations ran dry, frantic shoppers flocked to stores for essentials.
Matthew regained power as it swirled toward the US coast, upgraded a notch to Category Four on Thursday by the National Hurricane Center on its 1-5 scale.
In Myrtle Beach, South Carolina, the normally bustling resort turned into a ghost town as tourists loaded up cars, cut short vacations and fled north.
Despite the mass flight, officials warned a worrying number of people were not heeding the evacuation order.
"People do not seem to get it and are not leaving," Sheriff William D Snyder from Martin County, Florida, told NBC News.
Some 1.5 million coastal dwellers are under an evacuation order in Florida alone. More than a million others in South Carolina and other coastal states were also told to escape the path of the storm, which first made landfall in Haiti on Tuesday.
Mandatory evacuations were also ordered in six coastal counties in Georgia that are home to some 520,000 people.
Miami International Airport cancelled 90 per cent of its incoming and outgoing flights on Thursday.
Both presidential candidates sent out messages of support to those affected, with Republican Donald Trump saying "Please stay safe" while Democrat Hillary Clinton urged people to heed evacuation orders, tweeting: "Stay safe Florida."
The National Hurricane Centre said waves whipped up by the hurricane could reach as high as 18 feet (5.5 meters) -- nearly as tall as a two-storey building. Debris tossed into the air will be capable of blasting through buildings and cars, the NHC said in a bulletin.
Scott said the forecast is for storm surges of five to nine feet (1.5 to 2.7 meters), not counting the waves on top of that.
As Matthew barreled northwest, Caribbean nations continued the grim task of assessing damage and fatalities, with four dead in the Dominican Republic in addition to the surging toll in Haiti.
In Cuba, where some 1.3 million people were evacuated, there were no reported fatalities.
