0526 GMT February 23, 2020
Aerial footage showed scenes of catastrophic damage with hundreds of homes missing roofs, cars submerged or overturned, widespread flooding and boats reduced to matchwood, AFP reported.
Harrowing accounts emerged, with one survivor describing how he had watched his wife drown.
Announcing the updated death toll, Prime Minister Hubert Minnis warned the number would rise as he called Dorian "one of the greatest national crises in our country's history."
"Parts of Abaco are decimated. There's severe flooding, there's severe damage to homes, businesses, other buildings and infrastructure," he said.
Bahamas residents "endured hours and days of horror, fearing for their lives and the lives of their loved ones," Minnis said.
All tropical storm warnings for the islands had been discontinued, the National Hurricane Centre (NHC) said, as more accounts of the suffering it inflicted emerged.
The online Bahamas Press published video of flooding in the Rand Memorial Hospital in Freeport and said patients had been forced to evacuate the facility.
The US Coast Guard sent helicopters to Andros Island in the southern Bahamas to help with search and rescue operations as residents trapped in their homes by floodwaters issued distress calls.
But the runways at Grand Bahama International Airport in the island's largest city Freeport were under water, complicating rescue efforts.
The Miami-based NHC said the core of the storm "will move dangerously close to the Florida east coast and the Georgia coast through Wednesday night."
Dorian would move "near or over" the South and North Carolina coasts today through Friday morning.
President Donald Trump warned people against complacency.
"The US may be getting a little bit lucky with respect to Hurricane Dorian, but please don't let down your guard. As it heads up the coast, lots of very bad and unpredictable things can happen!" he tweeted.
"On the other hand, the Bahamas have been devastated," he wrote.
Dorian, which has dumped as much as 30 inches (76 centimeters) of rain on the Bahamas, was downgraded Tuesday morning to a Category 2 hurricane on the five-level wind scale.
But it is "expected to remain a powerful hurricane during the next few days," the NHC said.
A state of emergency has been declared in parts of the east coast for millions of US residents potentially in its path.
Late Tuesday, Trump tweeted: "I am getting the North Carolina Emergency Declaration completed and signed tonight. Hope you won't need it!"
The Pentagon said 5,000 members of the National Guard and 2,700 active-duty troops were ready to help out if needed.
Some mandatory evacuations were lifted Tuesday afternoon for parts of southern Florida, while further north, a large swathe of the state's coast – as well as that from mid-Georgia to southern North Carolina – remained under a hurricane warning.