Officials on Dominica said Hurricane Maria caused widespread damage to buildings. (Nigel R. Browne/Caribbean Emergency Management Agency/Reuters)

Relief agencies reached the hard-hit Caribbean nation of Dominica by air and sea on Wednesday after a direct hit by Hurricane Maria caused massive damage to homes and buildings, washed out roads, upended water pipelines and left at least seven people dead. 

Officials estimated that 70 to 80 percent of Dominica’s structures sustained storm damage, ranging from ripped-off roofs to near-total destruction. All intact public buildings were being converted into emergency shelters for scores of homeless residents. Americans, Canadians and others were waiting to be evacuated from the devastated island, officials said.

Aerial footage showed debris fields strewn across the island in the wake of Maria, which struck late Monday as a Category 5 hurricane with sustained winds above 160 mph.

“Tremendous loss of housing and public buildings. The main general hospital took a beating. Patient care has been compromised,” Hartley Henry, an adviser to Prime Minister Roosevelt Skerrit, wrote in a dramatic statement calling for international relief.

He said that “little contact has been made with the outer communities but people who walked 10 and 15 miles toward the [capital] city of Roseau from various outer districts report total destruction of homes, some roadways and crops.”  

A former British colony and a member of the Commonwealth, Dominica, with a population of about 72,000, was Maria’s first major victim as the hurricane blazed a deadly path through the Caribbean on the heels of two other brutal storms, Irma and Jose. The island is famous for its 365 rivers. Yet the same geography that has made it so picturesque has also made Dominica susceptible to severe flooding and mudslides. 

Tropical Storm Erika killed at least 30 people as it passed over the island in August 2015, and Hurricane David, a Category 3 hurricane that hit in 1979, killed 56. Neither was as strong as Maria.

Ronald Jackson, executive director of the Caribbean Disaster Emergency Management Agency, said at least 40 aid workers had reached the island by Wednesday to deliver medical supplies, tarps, food and water and to help launch a large-scale search-and-rescue operation. He estimated that there would be as many as 100 “boots on the ground” by Thursday morning. The Red Cross also planned to begin an aid operation on Thursday.

Jackson said the main port remained operational and able to receive aid ships. The island’s two airports were mostly intact, and at least one was open for emergency helicopter flights. 

But there were no air traffic controllers and, worse, the island’s main airport, Douglas-Charles, was largely cut off from the capital because of washed-out roads and damaged bridges. 

Still, the destruction on Dominica, Jackson said, did not appear to be as widespread as the recent havoc that Hurricane Irma wreaked on Barbuda, which was left uninhabitable. He compared Dominica’s damage to Irma’s hit on the British Virgin Islands, but said that Dominica’s terrain and washed-out roads were complicating the rescue effort.

“We are using every available means to get there,” he said. “Accessibility is the biggest challenge.”

As rescue workers accessed the island by boat and helicopter, Dominica remained largely cut off from the outside world. Communications were down, although five satellite phones were rushed to the island on Wednesday to help the isolated government respond to the crisis.

Skerrit, who captured attention on Monday night with dramatic Facebook posts as Maria ripped off the roof of his official residence, toured the island by helicopter Wednesday to assess the damage. Early Tuesday, he had described it as “mind boggling.”

“We will need help, my friend, we will need help of all kinds,” he wrote.

Godfrey Xuereb, who handles Dominica for the Pan American Health Organization, said the agency was preparing to assist with evacuations of people in medical need but that the geography and road damage presented hurdles that needed to be overcome.

“The road system has been compromised, so there’s obviously water damage, mudslides, rubble,” he said. “So even if the ports of entry are functional, the movement of people across the island is severely restricted.”

With communications severed, people outside Dominica were becoming desperate for word from family and friends there. David Charles, 46, a Dominica native residing in Britain, said he was frantically trying to obtain information on his children and parents still living on the island.

“Last time I heard from them was after 12 a.m. on the day of the hurricane,” he said. “We’re worried because we haven’t heard anything from our government officials. You would think they’d have a contingency plan to get the word out to so many concerned people with families back there. The lack of official information is simply worrying.”

Rachelle Krygier in Caracas, Venezuela, contributed to this report.