Thousands of homes were destroyed or damaged, hospitals crippled and a number of people remained stranded on rooftops awaiting rescue after it the small island nation was hit by the most powerful recorded storm in its history.
At least seven deaths were reported in the Bahamas, although relief workers warned this was likely to rise.
“It’s total devastation. It’s decimated. Apocalyptic,” said Lia Head-Rigby, who helps run a local hurricane relief group. “It’s not rebuilding something that was there; we have to start again.”
Ms Head-Rigby said her colleague in the hard-hit Abaco Islands told her there were “a lot more dead”, but she had no numbers.
Hubert Minnis, the country's prime minister, said he expected more deaths.
“We are in the midst of one of the greatest national crises in our country’s history,” he told a press conference. “No effort or resources will be held back.”
Red Cross spokesman Matthew Cochrane said more than 13,000 houses, or about 45 per cent of the homes on Grand Bahama and Abaco island, were believed to be severely damaged or destroyed.
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United Nations (UN) officials said more than 60,000 people on the hard-hit islands will need food. The Red Cross said some 62,000 will need clean drinking water.
“What we are hearing lends credence to the fact that this has been a catastrophic storm and a catastrophic impact,” Mr Cochrane said.
Rescuers used jet skis, boats and even a huge bulldozer to evacuate people from the storm’s aftermath across Grand Bahama. The bulldozer cradled adults and children in its digger as it churned through deep waters and carried them to safety.
Britain’s Royal Navy was rushing aid to the Bahamas while five US coast guard helicopters ran nearly-hourly flights to the stricken Abaco, flying at least 21 injured people to the capital’s main hospital.
With telephones down across Abaco and Grand Bahama islands, residents posted lists of missing loved ones on social media.
A single Facebook post by media outlet Our News Bahamas seeking the names of missing people had 1,600 comments listing lost family members since it went live on Tuesday morning.
Food may be required for 14,500 people in the Abaco Islands and for 45,700 people in Grand Bahama, the UN World Food Programme said in a statement.
Although the threat of a direct hit on Florida has all but evaporated, Dorian is expected to pass dangerously close to the other southern states later this week.
Even if landfall does not occur, the US National Hurricane Centre warned, the system is likely to cause storm surge and severe flooding.
“Don’t tough it out. Get out,” said US Federal Emergency Management Agency official Carlos Castillo.
Dorian was centred around 90 miles east of Daytona Beach, Florida, on Wednesday morning, and was moving north northwest at 8mph.
Hurricane-force winds extended up to 60 miles from its centre, while tropical storm-force winds could be felt up to 175 miles from the core.
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It also left one person dead in its wake in Puerto Rico before it slammed into the Bahamas on Sunday.
It tied the record or the strongest Atlantic storm ever to hit land, matching the Labour Day hurricane that struck Florida’s Gulf Coast in 1935.
Additional reporting by agencies