MARSH HARBOUR, Bahamas – Hurricane Dorian has left parts of tourism-dependent Bahamas in ruins and relief officials were preparing for an unfolding humanitarian crisis with the scale of the catastrophe only beginning to emerge.

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

Bahamas Prime Minister Hubert Minnis put the death toll at seven.

“We can expect more deaths to be recorded. This is just preliminary information,” Minnis told a news conference.

“Marsh Harbor has suffered, I would estimate, in excess of 60 percent damage to their homes,” Minnis said, referring to the port on Great Abaco. “The Mud, as we know, has been completely destroyed or decimated,” he said in reference to a shantytown known as The Mud and The Peas.

One Twitter post described how “victims are being loaded on flatbed trucks across Abaco,” showing a rain-blurred photo of limp bodies strewn across a truck bed. Other messages on described whole communities being swept away.

Minnis said he saw people waving for help in a community near Coopers Town on Great Abaco, after it had been cut off by flooding.

“There were around 30 people trapped and waving yellow flags, sheets and shirts to bring our attention to their survival,” said Minnis.

A video showed a storm surge rising up inside a two-story home, the sofa and other furniture floating toward the second floor. Another showed residents trying to swim from one home to another through the surge.

Reports from Grand Bahama island and its main town of Freeport have been more sketchy. Relief agencies have been unable to get through because of weather conditions, Minnis said.

The Miami-based U.S. National Hurricane Center said storm surges in Grand Bahama were 12 feet to 18 feet (3.7-5.5 m) above normal tide levels.

With telephones – including emergency lines – down on Abaco and Grand Bahama islands, residents posted lists of missing loved ones across social media platforms.

A single Facebook post inviting the names of missing people by local media outlet had 1,600 comments listing lost family members since it went live late on Tuesday morning.

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, said Theo Neilly, the Bahamian consul general in Washington. Dorian has battered the Bahamas for the past three days. “We expect it to be very devastating and the damage to be extreme,” Neilly said.

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, in the strongest storm ever to hit the Bahamas.

Food will be required for 14,500 people in the Abaco Islands in the northern Bahamas and for 45,700 people in Grand Bahama, 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. Agency for International Development said on Twitter it was “airlifting critical relief items – like plastic sheeting, hygiene kits, and water containers” from Miami to the Bahamas. The U.S. Coast Guard said four of its helicopters were assisting in the humanitarian effort.

Dorian, which killed one person in Puerto Rico before bashing into the Bahamas on Sunday, is tied for the second-strongest Atlantic storm to make landfall with Gilbert (1988), Wilma (2005) and the 1935 Labor Day hurricane.