Marsh Harbour: Hurricane Dorian grew in size and picked up speed on Tuesday, and was forecast to come "dangerously close" to Florida's coast after pounding Grand Bahama Island for about a day, killing at least five people.

Dorian, which over the weekend had been one of the most powerful Atlantic hurricanes on record, inundated homes with floodwater in the Abaco Islands in the northern Bahamas ahead of its expected advance on the US East Coast, where more than a million people had been ordered evacuated.

The hurricane weakened early on Tuesday to a Category 2 on the five-step Saffir-Simpson Wind Scale, with maximum sustained winds of 110 miles per hour (175 km per hour), the US National Hurricane Centre said. It was moving northwest at 2 mph (1.6 kph), below walking speed, and was about 105 miles (170 km) east of Fort Pierce, Florida.

The NHC warned that Dorian remained dangerous despite the reduced wind speed.

"The headline for this #Dorian advisory is NOT that the wind speed has slightly decreased," it said on Twitter. "The combined wind, surge, and floods hazards are the same or even worse since the hurricane has become larger."

The exact toll of the devastation in the Bahamas will not be clear until the storm passes and rescue crews can get on the ground. The storm lashed the islands for almost 24 hours, and the death toll was likely to rise, said Iram Lewis, a member of Parliament, in an interview with CNN.

"It is safe to say, unfortunately, that that number will go up," Lewis said, adding that extensive floodwaters were making it difficult for rescuers to reach stranded residents. He saw extensive numbers of destroyed houses, felled trees and stunned residents as he surveyed the area he said, adding "It is just unbelievable."

As many as 13,000 homes in the Bahamas may have been destroyed or severely damaged, the International Federation of Red Cross and Red Crescent Societies said.

Efforts to reach officials in the Bahamas by phone on Tuesday were unsuccessful.

'Don't know what to do'

Dorian was expected to churn toward Florida by day's end, before bringing its powerful winds and dangerous surf along the coasts of Georgia, South Carolina and North Carolina by late Thursday.

Forecasters have told Floridians not to become complacent because the storm is now predicted to stay off the coast.

Dorian could drive seawater inland as it approaches, with parts of the northern Florida and Georgia coasts seeing as much as 7 feet (2.1 meters), said NHC Director Ken Graham, urging residents of coastal areas to obey any evacuation orders.

Hurricane-force winds extended 60 miles (100 km) from the storm's core, with still-dangerous tropical storm-force winds felt for 175 miles (280 km) from its center.

Nine counties in Florida have issued mandatory evacuation orders. They included parts of Duval County, which includes Jacksonville, one of Florida's two biggest cities, and some areas in Palm Beach County, home to Trump's Mar-a-Lago resort.

After days of warnings to flee a storm that at its peak was rated at the top of the scale of hurricane strength, many residents of Florida's coast remained unsure whether to wait it out or evacuate.

"I know it's a mandatory evacuation, but everyone I talked to is staying, and I don't know what to do. But I'm going to be ready and packed up in case I need to get on the road if they close those bridges," Linda Cassano, a 53-year-old beautician who lives on Jacksonville Beach said as she stocked up on water and food. "What deterred me is everything was open, the garbage man came today, the post office was delivering, so those things kind of make you indecisive."

Further north, the streets of Sea Island, Georgia, were largely empty on Tuesday after many visitors heeded evacuation orders, said Kathryn Ross, owner of the Pelican Market grocery store.

"It's like a ghost town. People really packed it up and left. I went running - I was running partly in the road because there was no one there," Ross said in a phone interview. "I think people know the drill and have places set up to stay."

Orlando International Airport ceased commercial operations because of the storm, it said in a statement.

Walt Disney World Resort in Orlando will close early on Tuesday, it said in a statement.

The governors of Georgia and South Carolina had ordered evacuations of some coastal counties.

Dorian was tied with Gilbert (1988), Wilma (2005) and the 1935 Labor Day hurricane for the second-strongest Atlantic hurricane on record, based on maximum sustained winds. Allen in 1980 was the most powerful, with 190-mile (306-kph) winds, the NHC said.