The final death toll from Hurricane Dorian in the Bahamas could be “staggering,” a government minister has said as the storm lashed North Carolina in the US on Friday with torrential rain and fierce wind.

Bahamian Prime Minister Hubert Minnis told CNN on Thursday that at least 30 people were killed in the storm, which caused what he called “generational devastation.”

Extra morticians and refrigerated coolers to store bodies were being sent to the region to help authorities cope with the deadly impact, Health Minister Duane Sands told local media.

Of the final number killed, he declared: “Let me say that I believe the number will be staggering.”

An AFP team in the town of Marsh Harbour on Great Abaco on Thursday saw scenes of catastrophic damage with homes reduced to matchsticks, overturned cars, fields of jumbled debris, widespread flooding and beached boats.

Dorian was a Category 5 hurricane — the highest on the five-level wind scale — when it slammed into the northern Bahamas on Sunday, leaving a trail of immense destruction.

Thousands have been left homeless, while the United Nations said 70,000 were in immediate need of aid.

The Miami-based National Hurricane Center (NHC) on Friday downgraded Dorian to a Category 1 storm as it whipped the Outer Banks — finger-like barrier islands off the coast of North Carolina. It warned of life-threatening storm surges and dangerous winds, and said some areas have been hit with flash flooding.

It warned that although weakening, Dorian was still packing winds of 90 miles per hour (150 kilometres per hour), with some areas of the Carolina coast forecast to get between six and 12 inches of rain.

Authorities in Florida — which was largely spared by the storm — blamed six more deaths on the hurricane, US media reported, though they occurred as the victims were preparing for the storm's arrival or were evacuation-related.

'Hell everywhere'

The slow-moving monster storm also lashed the coast of South Carolina on Thursday and the historic city of Charleston, spawning several tornadoes but there were no immediate reports of casualties.

Many residents of coastal areas in the Carolinas heeded evacuation orders while others battened down their homes with plywood and prepared to ride out the tempest.

The storm was expected to move to southeast New England on Friday night and Saturday morning, and then across Nova Scotia late Saturday.

US President Donald Trump tweeted that he had spoken to the governors of North and South Carolina, telling them he is “ready to assist.”

The full extent of the damage in the northern Bahamas was becoming known on Thursday as rescue teams fanned out searching for survivors and bringing relief to victims.

“It's hell everywhere,” said Brian Harvey, a Canadian from Montreal, told AFP in Great Abaco.

“I was on my sailboat,” Harvey said. “I lost everything.” “We need to get out of here,” he added. “It's been four or five days. It's time to move and get out of here.”

Steven Turnquest, who arrived in Nassau from Marsh Harbour with his four- and seven-year-old sons after weathering the storm, told AFP he was grateful to be alive.

Speaking of his sons, Turnquest said he prayed to God to “take me and let them live.” “I survived the hurricane holding on to a door.”

Amid fears of lawlessness in the ravaged storm zone, Prime Minister Minnis warned that any looters will be prosecuted “to the fullest extent of the law,” and additional police and defense force officers deployed.

US and British helicopters were conducting medical evacuations, aerial assessments to help coordinate relief efforts, and reconnaissance flights to assess the damage.

The US Coast Guard said it had rescued 201 people in the Bahamas as of Thursday.

The UN's World Food Programme said it had eight tons of ready-to-eat meals poised to arrive in the Bahamas.