NASSAU, Bahamas — Houses torn open. Cars, boats and heavy equipment tossed and crumpled. Whole communities flooded, and flattened. Twenty dead, according to the official count, and more expected.

The government in this nation of 400,000 sounded the all-clear from Hurricane Dorian on Wednesday morning, lifting the tropical storm warning for Grand Bahama, the Abacos, Bimini and other battered islands.

As the storm, which slammed into the Bahamas on Sunday as a Category 5 hurricane and spent a devastating 40 hours grinding across Grand Bahama, finally lurched onward to the United States, the full scope of the destruction became clearer.

“We are in the midst of one of the greatest national crises in our country’s history,” Prime Minister Hubert Minnis said Tuesday night.

The official death toll rose to 20 as of Wednesday night. The Bahamas Minister of Health, Duane Sands, told The Washington Post that 17 dead were reported in the Abacos and three were reported in Grand Bahama. But that total is expected to rise as search efforts continue in areas of the islands that were decimated.

Gail Woon returned to her flooded home in Freeport on Grand Bahama on Wednesday. She described a harrowing week.

As Dorian struck, the 60-year-old marine biologist spent a “taxing” night in a shelter. Someone opened a window, and the roof collapsed. She and the others there ran to a church — one of the few shelters that didn’t collapse or flood.

“Buildings here are only built to withstand 150-mph winds,” she said. “We have no chance.”

Woon said she had lived through Hurricanes Frances and Jeanne in 2004.

“This was nothing like those,” she said. “This was something that we never experienced before.”

Family members gathered at the helicopter terminal of Nassau’s international airport awaiting evacuees from the Abacos islands.

Ralanda McKinney, a 25-year-old Abacos transplant living in Nassau, was waiting for news of her mother and father, who live in the Abacos community of Treasure Cay.

A neighbor who was evacuated with severe injuries had told her that he had seen them at a shelter that was running out of food.

“I don’t care about possessions,” McKinney said. “I just want to see their faces.”

Nine U.S. Coast Guard cutters were heading for the Bahamas Wednesday. Coast Guard helicopters have been airlifting patients from clinics on the hardest-hit islands to medical facilities in Nassau. The British Royal Navy, aid groups and volunteers were joining in rescue and relief efforts.

“The magnitude of destruction is catastrophic,” said Lt. Cmdr. Kristopher Ensley, the captain of the 154-foot Coast Guard Cutter Paul Clark. “It’s tragic.”

Dorian was moving at 8 mph north-northwest off the Florida coast north of the Bahamas at 8 a.m. Wednesday, according to the National Hurricane Center. It has been downgraded to a Category 2 hurricane with maximum sustained wind of 105 mph. It was forecast to continue moving up the coast, and it could make landfall in the Carolinas late Wednesday or Thursday.

Minnis, who flew over the Abacos island group on Tuesday, described the wreckage there. Sixty percent of houses in Marsh Harbour damaged. The Mudd, a shantytown of Haitian workers, completely destroyed. The airport underwater.

Minnis put out a call for volunteer rescuers on Grand Bahama, and he planned to meet Wednesday morning with aid groups.

At the helicopter terminal, Bahamians were becoming increasingly frustrated with the official response.

Rayven Bootle, 18, was waiting for word from her mother, grandmother and others in Treasure Cay.

She said the Abacos community outside the island had organized donations of water, food and toiletries but the government was preventing them from taking them there.

“It’s been days. Dorian is gone,” she said. “Come on, we need to get in.”

Sandra Cooke has relatives on keys near the Abacos. Communication has been difficult, she says, and their situation is dire.

“It’s all gone,” she said. “They, the prime minister, the authorities, aren’t even talking about those keys, they haven’t even flown over those keys. It’s flat like the ground we’re standing on.”

The Coast Guard moved more than 20 cutters to shelter in Key West, Fla., before the storm so they could be deployed quickly in its wake. The 418-foot National Security Cutter James arrived early Wednesday.

The Coast Guard routinely patrols near the Bahamas, especially Bimini and Freeport, but rescuers faced many unknowns Wednesday.

Storm surges made charts unreliable and coastal depths unpredictable. Aerial photos showed that much of the debris, possibly including parts of roofs, buildings and submerged boats, landed in the ocean.

“You don’t really know what to expect,” said Ardy Effendi, executive officer of the Paul Clark. “We can’t just push through a lot of debris.”

The Coast Guard was still fielding requests from the Bahamian government, which was attempting to assess its most immediate needs.

The Coast Guard asked that people in danger in the Bahamas call 911 or 919, the emergency numbers here. People in the United States attempting to check on relatives and friends may call the State Department’s Office of Overseas Citizens Services at 888-407-4747.

Sacchetti reported from aboard the U.S. Coast Guard Cutter Paul Clark in the Atlantic Ocean. Rachelle Krygier contributed from Miami.