Survivors of Hurricane Matthew put on their Sunday finest and picked their way through downed power lines to sing praise and pray in ruined churches, while desperation grew in other parts of devastated Haiti and international rescue efforts began ramping up.

Haitian authorities were still unsure of the extent of the disaster, with some communities still cut off. But tens of thousands of homes were obliterated and the dead number in the hundreds.

Guillaume Silvera, a senior official with the Civil Protection Agency in the storm-blasted Grand-Anse Department, which includes Jeremie, said at least 522 deaths were confirmed there alone — not including people in several remote communities still cut off by collapsed roads and bridges.

National Civil Protection headquarters in Port-au-Prince, meanwhile, said Saturday its official count for the whole country was 336, which included 191 deaths in Grand-Anse.

Despite the loss, families packed what remained the city's churches, many seated in pews under open sky because Matthew ripped away roofs and even walls of the sanctuaries. At least one was so badly damaged that worshippers set up an altar and prayed outside.

Elise Pierre, who said she was about 80, said she believed it was a divine miracle that she and her loved ones survived.

"If God wasn't protecting us we'd all be gone today, blown into the ocean or up into the mountains," said Pierre, whose straw hat almost concealed a gash on her forehead she sustained when her sheet metal roof collapsed during the height of Matthew's fury.

The sound of hammering could be heard on nearly every street in Jeremie, a city near the tip of Haiti's southwest peninsula, as people patched their roofs as best as they could.

On one corner, Jameson Pierre was mixing cement and making them into blocks. The 22-year-old storm refugee whose family was stuck in an emergency shelter, saw at least one bright side.

"There will be lots and lots of jobs since so many homes were knocked down. I've been working for the last three days straight," he said in the fierce morning sun. He said he was getting about a dollar a day.

The first three of five cargo planes of humanitarian aid from the United States have arrived at the Toussaint Louverture airport in the capital Port of Prince. They were carrying 480 metric tons of relief supplies, including 20,000 hygiene kits, 18,000 sets of kitchen utensils for cooking, 40,000 blankets and 500 rolls of plastic sheeting.

The airstrip in Jeremie is unable to accommodate large cargo planes, so relief was being ferried to the devastated city by helicopter. Three of nine U.S. helicopters had arrived in Jeremie by Sunday, bringing rice and cooking oil, among other things.

"I lost everything I own in this hurricane. I just came here to get some help," said subsistence farmer Markus Bagard, one of roughly 200 Haitians standing outside the airstrip watching the helicopters be unloaded.

Many of the villages in the southwestern peninsula are difficult to reach. And people are growing increasingly desperate after losing everything when the storm ripped through the area on Tuesday.

Dony St. Germain, an official with El Shaddai Ministries International, said young men in villages off the road between the southern city of Les Cayes and Jeremie were starting to put up blockades of rocks and broken branches to halt the convoys.

"They are seeing these convoys coming through with supplies and they aren't stopping. They are hungry and thirsty and some are getting angry," said St. Germain.

A civil protection convoy carrying food, water and medication from Les Cayes to Jeremie was attacked by gunmen in a remote valley where there had been a bad mudslide, Fridnel Kedler, the coordinator for the Civil Protection Agency in Grand-Anse, said on Sunday. The convoy's driver was pistol whipped and all the relief supplies stolen.

Kedler attributed the armed robbery to desperation in many rural communities that have not yet received aid. He said that authorities will try to reach marooned communities west of Jeremie on Monday.

Government officials estimate that at least 350,000 people need assistance, and concern was growing over an increase in cholera cases following widespread flooding unleashed by Matthew. An ongoing cholera outbreak has already killed roughly 10,000 people and sickened more than 800,000 since 2010, when the infectious disease was introduced into the country's biggest river from a U.N. base where Nepalese peacekeepers were deployed.

Maria Sofia Sanon, a health worker overseeing the open-air cholera treatment center in a corner of Jeremie's main hospital, said they were ill-equipped to deal with patients. The area was strewn with broken tree branches, and a group of young mothers sat outside holding up the arms of their glassy-eyed children being rehydrated via IVs.

"They're not supposed to be in the sun, but we have no more beds," Sanon said.

The World Food Program says there has been massive destruction of crops. Hospitals and clinics have been damaged or destroyed as they struggle to deal with an increase in patients with injuries sustained during the storm as well as an apparent increase in cholera. UNICEF said that in Grand-Anse alone there were 66,000 houses destroyed and 20,000 heavily damaged.

"Information gathered from various sources in the field suggests that the human toll (dead and injured) will be heavier than the current official figures," the agency said in a report.

Jocelyne Saint Preux was part of the crowd that lined up in an orderly fashion to get food as aid began.

The mother of three children whose home was destroyed said officials were handing out wheat, beans, oil and salt.

"Yes, they brought food, but it's not sufficient," she said. "There's no water. There's no charcoal."

People in Les Cayes, as well as the southern community of Port Salut, said little to no aid has reached them.

Fisherman Dominique Pomper said the mayor came to distribute some rice but that was it. Among other things, he people here needed power restored and water. The ocean has intruded into their wells and made their own supplies undrinkable. Many don't want to drink other sources of water because of fears of cholera.

Pomper said he tried to stay at home with his wife and family during the storm but they eventually fled as the water rushed into their house. The 61-year-old said it was the worst night of his life but that he would never leave his seaside village.

"We are fishermen here, our job is the water. We can't run away from the water," he said.