NEW YORK — The first reports to arrive were of vast flooding and destruction, rivers of brown water pulsing through streets, and homes shorn of tin roofs. Eventually, the talk turned to livestock lost, a veritable fortune for those living in the poorest country in the Western Hemisphere.

But three days after the worst storm to strike Haiti in more than 50 years, the death toll is rising, and fast. From initial estimates of five dead, the government is now saying 283 people have been killed in Hurricane Matthew and its aftermath, the worst natural disaster to strike the nation since the earthquake of 2010.

The storm left a broad tableau of devastation: houses pummeled into timber, crops destroyed, and stretches of towns and villages under several feet of water. In the southern city of Jérémie, 80 percent of the buildings were destroyed.

The numbers of known dead soared as officials and aid workers ventured deeper into areas cut off from rescue efforts in the south, discovering more bodies interred in flooded homes and streets. Until Thursday, there had been no connection to the south of the country — neither electronic nor physical, owing to severed phone lines and collapsed bridges.

“This is a very, very partial assessment of the damage and death,” Annick Joseph, the country’s interior minister, said during a news conference earlier in the day. Among other things, he added, dead were also being discovered in the mountains of the country, where communities are more isolated.

The sudden surge in numbers reflects, in some ways, the very nature of the many challenges that Haiti faces. The country’s infrastructure had been in decline for decades, even before the earthquake and other storms weakened it further. A fragile communications system, too, was unreliable even in the best of times.

These challenges and others are part of the reason the government so vastly underestimated the number of deaths, and why, many think, the number will continue to rise. More fundamentally, it meant that there was little the government was capable of doing to prepare — and to respond.

Enzo di Taranto, the head of the UN Office for the Coordination of Humanitarian Affairs in Haiti, said there would “be a severe impact on the environment, agriculture, and water systems.”

“Schools, hospitals, and police stations, everything that was there when the hurricane hit was in some way damaged, because of the strengths of the wind,” di Taranto said.

On Wednesday, officials said the hurricane’s damage had forced them to postpone an already-delayed presidential election set for Sunday in the country of 11 million.

This latest disaster revives unresolved questions that continue to haunt the country from the 2010 earthquake, when international aid groups practically usurped the role of the government.

The government has been clear that this time around it will take the lead on coordinating aid, as donors bring in fresh water, food and money. Yet that approach, too, has its limitations.

The current government is an interim administration that was to be replaced in the Sunday election.

Aid groups especially fear cholera, a waterborne infection that has stubbornly plagued Haiti since shortly after the earthquake, when it was believed to have been inadvertently introduced by UN peacekeepers assigned to the country.

According to the United Nations, more than 1 million people have been affected by the storm in Haiti — and at least a third of them will require humanitarian assistance.

Di Taranto’s UN office, which is helping coordinate assistance between the government and humanitarian groups, said that more than 15,000 people were in emergency shelters.

The Civil Protection Force of Haiti put the figure countrywide at closer to 27,000 people, with the majority in the south. At least 20,000 homes were wrecked and hundreds of Haitians were injured, officials said.