The havoc wreaked on the Bahamas by Hurricane Dorian is becoming devastatingly clear in footage and pictures being shared across social media.

Dorian hit the island nation as a category five storm on Sunday (local time) and stalled on Monday and Tuesday.

One of the most powerful storms to hit the Bahamas, it killed at least seven people. Relief officials are preparing for a humanitarian crisis – but full scale of the disaster is not yet known.

Footage and information is only now beginning to emerge from the devastated islands, which have been cut off from most communication for days.

Video footage showed flood waters raging outside homes on Grand Bahama island, with roofs ripped from buildings and neighbourhoods devastated by the gale-force winds.

Watch below:

Aerial video recorded over the Bahamas’ Great Abaco Island showed kilometre upon kilometre of flooded neighbourhoods, pulverised buildings, upturned boats and shipping containers scattered like Lego toys. Many buildings that had not been flattened had walls or roofs partly ripped away.

While its winds had diminished to a category two storm, Dorian expanded in size and picked up speed on Tuesday. Forecasters said it would come “dangerously close” in the next 36 hours to Florida’s east coast, where more than a million people have been ordered to evacuate.

In the Freeport area of Grand Bahama island, people on jet skis and boats tried to rescue hundreds of others whose homes had flooded on the low-lying island, a CNN correspondent said.

Tropical-storm-force winds hampered the efforts, flipping over some of the jet skis. The correspondent said he had spoken to a man whose wife had died of hypothermia after being trapped in their flooded home for hours and others who said they had watched people swept away by the storm surge.

In the US, the National Hurricane Centre said Dorian had sustained winds of 175km/h and was moving north-west at 8km/h, as it churned about 170 kilometres east of Vero Beach, Florida.

“Dorian is expected to remain a powerful hurricane during the next couple of days,” the NHS said.

The exact toll of the devastation in the Bahamas will not be clear until the storm completely passes and rescue crews can get on the ground.

“We have not been able to assess the damages on Grand Bahama Island just yet. We expect it to be very devastating and the damage to be extreme,” said Theo Neilly, the Bahamian consul general in Washington.

He added that the sea surge from the storm was high and people were still trapped in their homes and attics.

Floodwaters at the Rand Memorial Hospital in Freeport Grand Bahama – Emergency Room. Hurricane Dorian forced patients to evacuate the hospital. #DORIAN #HOSPITAL #hurricane pic.twitter.com/cUmxEsjn2Q

— Bahamas Press (@Bahamaspress) September 3, 2019

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

The Abaco Islands in the northern Bahamas might require food for 14,500 people and Grand Bahama for 45,700 people, the UN World Food Program said. The preliminary estimates were based on an assessment by representatives from Caribbean countries, the WFP and other organisations.

Heart-wrenching video shows the moment a journalist and his family were forced to abandon their home in the Bahamas and make it through chest-deep flood waters to get to safety during Hurricane Dorian.

LATEST: https://t.co/N1NWx1gYb8
HOW TO HELP: https://t.co/0sJCyvF35o pic.twitter.com/s2Ja6MG9zx

— WSVN 7 News (@wsvn) September 3, 2019

The US military has been authorised to provide logistics, health and engineering support to the Bahamas for up for 14 days if needed, General Terrence O’Shaughnessy, the head of US Northern Command, said.

The US Coast Guard said four of its helicopters were assisting in the humanitarian effort.

-with AAP