Emergency teams in Haiti struggled Wednesday to reach hurricane-ravaged areas cut off by washed-out bridges and mudslides after Hurricane Matthew roared over the nation’s western tip and began a devastating ­island-hopping path that arcs toward the U.S. coast.

The full extent of Matthew’s blow to Haiti remained unclear, with communications severed to some regions in the Western Hemisphere’s poorest nation — where tens of thousands of people still live in tents after an earthquake six years ago killed 200,000 people.

At least 16 deaths — including at least 10 deaths in Haiti and four in the neighboring Dominican Republic — have been blamed on the hurricane, according to Reuters. It packed winds of up to 145 mph when it swept over Haiti on Tuesday and then hit Cuba and the Bahamas. A slightly weakened Matthew was expected to make landfall in Florida on Thursday.

“What we know is that many, many houses have been damaged,” Haitian Interior Minister François Anick Joseph said. “Some lost rooftops and they’ll have to be replaced, while others were totally destroyed.”

John Hasse, national director of the aid group World Vision in Haiti, estimated “thousands of houses destroyed or damaged” in the areas hardest hit. The Haitian government said at least 350,000 people were in need of immediate help around the country, the United Nations said. At the same time, fears rose of possible outbreaks of cholera or other diseases.

Samuel Darguin, a worker with the aid group Haitian American Caucus-Haiti, said relief convoys were prevented from reaching many areas because bridges had been swept away by floodwaters.

Local teams in the isolated regions were in “search-and-rescue mode,” he said, with reports of people missing. That suggested the death toll could rise.

Faced with the devastation, Haiti’s electoral council on Wednesday postponed a long-delayed presidential election that was scheduled for Sunday. There was no immediate word on when it would be held. Many schools and churches designated as polling places were being used as shelters.

International aid was underway, meanwhile, with a focus on shelter and clean water. The U.S. Navy has sent three ships to Haiti, including an aircraft carrier and a hospital ship. About 300 Marines were aboard the USS Mesa Verde, an amphibious transport vessel.

The United States announced $1.5 million in aid available to the Caribbean countries in Matthew’s wake. Disaster response teams were pre-positioned with some supplies and were assessing the damage and urgent relief needs, said Kenneth Merten, deputy assistant secretary of state for the Western Hemisphere and a special coordinator on Haiti.

Beyond food, the aid includes shelter, blankets, and kits for hygiene and water purification to help prevent the spread of cholera, said David Harden, an official with the U.S. Agency for International Development.

Venezuela, battered by a major economic crisis, mobilized an airlift of humanitarian supplies, and the British-based group Oxfam concentrated on sanitation and clean water efforts.

Many people live in rudimentary shacks crowding the hillsides that are especially vulnerable to the high winds and lashing rains of a hurricane — as well as the landslides that often occur afterward in rain-loosened soil.

In Port-au-Prince, the capital, water remained knee-deep in some low-lying districts. Boats and other flotsam were wedged amid stores and homes.

Mourad Wahba, the U.N. deputy special representative for Haiti, called Matthew “the largest humanitarian event” in the nation since the earthquake and said that “much of the population” has already been displaced.

Jean-Michel Vigreux, director in Haiti for the aid group CARE, said estimates on damage have reached as high as $1 billion even before the full extent of the devastation is tallied.

“It is very scary,” he said in a statement.

By Wednesday evening, Matthew was lashing the southern Bahamas with maximum sustained winds of 120 mph and heavy rain. The storm — now downgraded to a Category 3 hurricane — was heading northwest at 12 mph on a path that would take it close to the east coast of Florida by Thursday evening, the National Hurricane Center reported.

In Cuba, the hurricane destroyed dozens of homes and damaged hundreds of others in Baracoa, a city on the country’s eastern tip. Authorities prepared for the storm by moving people out of threatened coastal areas.

At the Guantanamo Bay Naval Base, about 700 family members of U.S. personnel and others were evacuated from the area before Matthew hit. The storm knocked down trees there and flooded roads but caused no injuries or major damage, a base spokeswoman said.

Officials in the Bahamas urged residents to move to higher ground amid the dozens of low-lying islands in the archipelago, and residents of the capital, Nassau, braced for Matthew’s wrath as forecasters predicted a storm path close to the city.

Citing a combination of dangerous storm surges and large, destructive waves, the National Hurricane Center warned of “a danger of life-threatening inundation” on Thursday and Friday along parts of Florida’s east coast from North Palm Beach to Fernandina Beach.

The governors of Florida, Georgia, South Carolina and North Carolina declared states of emergency, and at least 500,000 people in Florida and South Carolina were asked Wednesday to evacuate low-lying coastal areas.

Carol Morello, William Branigin and David Filipov contributed to this report.