The fiercest Caribbean storm in nearly a decade slammed into the Bahamas early on Thursday, intensifying as it barreled towards the southeast U.S. coast where a mass exodus was under way with millions heeding warnings to flee inland.

Roadways in Florida, Georgia and North and South Carolina were packed and gas stations and food stores ran out of supplies as Hurricane Matthew approached, packing sustained winds of about 115 miles per hour (185 km per hour), storm surges and heavy rain.

Matthew, which killed at least 26 people and damaged swathes of homes in southern Haiti, was predicted to strengthen from a Category 3 to 4 storm en route to eastern Florida. Landfall was expected there on Thursday night, the U.S. National Hurricane Center said.

"Everyone in our state must prepare now for a direct hit," Florida Governor Scott told a news conference in Tallahassee on Wednesday. "If Matthew directly impacts Florida, the destruction could be catastrophic and you need to be prepared."

The four states in the hurricane's path declared states of emergency enabling their governors to mobilize the National Guard. Shelters in Florida, Georgia and South Carolina opened their doors after authorities, along with President Barack Obama, urged locals to evacuate their homes.

Federal emergency response teams were coordinating with officials in all four states and stockpiling supplies, Obama said.

Scott requested that Obama declare a pre-landfall emergency for Florida, which would bring resources including as food, water and waterproof coverings and double the active National Guard force to 3,000.

Schools and airports across the region were closed on Thursday and some hospitals evacuated patients, according to local media.

'ALL BOARDED UP'

In all, more than 12 million U.S. residents were under a hurricane watches and warnings, according to the Weather Channel.

In Florida, fuel stations posted "out of gas" signs after cars waited in long lines to fill up.

"Every gas station I went to is empty," said motorist Charles Bivona in a Tweet late Wednesday. "Here comes Hurricane Matthew. Um, yikes."

Others, meanwhile, prepared to wait out the storm.

People stocked up on water, milk and canned goods, emptying grocery store shelves, footage from local media showed.

Residents and business owners boarded up windows with plywood and hurricane shutters and placed sandbags down to protect property against flooding.

"All boarded up and ready to bunker down. God be with us," West Palm Beach Florida resident Brad Gray said in a Tweet.

The National Hurricane Center said it was still too soon to predict where in the United States Matthew was likely to do the most damage.

On Tuesday and Wednesday the storm whipped Cuba and Haiti with 140 mile-per-hour (230 kph) winds and torrential rains, pummeling towns and destroying livestock, crops and homes.

The devastation in Haiti prompted authorities to postpone a presidential election.

PHOTO CAPTION

People walk down the street next to destroyed houses after Hurricane Matthew passes Jeremie, Haiti, October 5, 2016.

REUTERS