(New throughout, adds details on destruction in Bahamas, latest NHC update)
By Dante Carrer
MARSH HARBOUR, Bahamas, Sept 3 (Reuters) - Hurricane Dorian grew and picked up speed, churning on a path that forecasters said would come "dangerously close" to Florida later on Tuesday after the storm battered the northern Bahamas, killing at least five people.
Dorian over the weekend was one of the most powerful Atlantic hurricanes on record, pulverizing buildings and flooding parts of the Abaco Islands in the northern Bahamas.
On the U.S. East Coast, more than a million people have been ordered evacuated ahead of its expected advance.
The hurricane weakened early on Tuesday to a Category 2 on the five-step Saffir-Simpson Wind Scale, packing maximum sustained winds of 110 miles per hour (175 km per hour) and moving northwest at 5 mph (8 kph), the Miami-based National Hurricane Center said.
The NHC warned that Dorian remained dangerous as it churned about 105 miles (116 km) east of Fort Pierce, Florida. It said the hurricane was moving offshore, nearly parallel to Florida's east coast.
In the Bahamas, Dorian lashed the islands, including Great Abaco and Grand Bahama Island, for about 24 hours. Aerial video recorded over Great Abaco showed widespread devastation, with buildings flattened or missing roofs and walls, boats upturned and shipping containers scattered about like toy bricks. Entire neighborhoods could be seen under water.
The exact toll will not be clear until the storm completely passes and rescue crews can get on the ground.
Theo Neilly, the Bahamian consul general in Washington, said the damage on Grand Bahama was expected to be "very devastating." He said many people were still trapped in their homes and attics because of a strong sea surge.
Although Dorian is moving away from Grand Bahama, forecasters said dangerous winds and a life-threatening storm surge would persist through the evening.
Iram Lewis, a Bahamian member of Parliament, said on CNN the death toll would likely climb.
"It is safe to say, unfortunately, that that number will go up," Lewis said. "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.
Abaco may require food for 14,500 people and Grand Bahama for 45,700 people, the U.N. World Food Programme said in a statement. The preliminary estimates were based on an assessment by representatives from Caribbean countries, the WFP and other organizations.
The U.S. military has been authorized to provide logistics, health and engineering support to the Bahamas for up for 14 days if needed, General Terrence O'Shaughnessy, the head of U.S. Northern Command, told reporters on Tuesday.
Efforts to reach officials in the Bahamas by phone on Tuesday were unsuccessful.
Dorian was expected to bring hurricane conditions to Florida overnight, before unleashing 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. 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 (95 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 the storm, 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.
There have already been some power outages in Florida. Governor Ron DeSantis said over the weekend that Florida Power & Light has 17,000 workers standing by to restore power once the storm passes.
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, South Carolina and North Carolina have 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.
Reporting by Dante Carrer in Marsh Harbour, Bahamas, Zachary Fagenson in Jacksonville, Florida, Gabriella Borter in Titusville, Florida, Peter Szekely, Matthew Lavietes, Scott DiSavino and Jonathan Allen in New York, Rich Mckay in Atlanta and Idrees Ali in Washington, writing by Scott Malone and Paul Simao; Editing by Gareth Jones, Nick Zieminski, Jonathan Oatis and David Gregorio