Corpses were hanging from palm trees and people died trapped in their submerged homes in the devastated Haitian town of Mapou, according to relief officials, who struggled Friday to bring aid to an area where flash floods have brought a rising and still undetermined death toll.

Haitian officials said that hundreds were reported missing in Mapou and about 25 in the surrounding hamlets of a remote and severely deforested region near the border with the Dominican Republic, about 30 miles southeast of this capital city. They said the flooding was the worst natural disaster to hit the island of Hispaniola in years.

Bernard Barrett, a spokesman for the International Committee of the Red Cross, said all casualty figures were preliminary, but that almost 1,500 people were missing or dead in both countries, based on compiled reports. In the Jimani area of the Dominican Republic, 361 bodies have been recovered and 352 were missing, he said. In Mapou, 650 were missing and "while we can presume many are dead" the bodies had not been recovered. In the neighboring Haitian town of Fond Verettes, 158 were missing and many were presumed dead, he said.

"The population there is in a state of shock," said John Bevan, a U.N. official in Haiti, whose teams are tending to survivors in Mapou and Fond Verettes.

Cristina Estrada, a spokeswoman for the International Red Cross in the Dominican Republic, said that many of the victims from Jimani were washed downriver into Lake Enriquillo, which she said was the only lake in the country with crocodiles. She said that would complicate recovery of the corpses.

Kate Scannell Michel of the relief organization World Vision said officials who have visited Mapou and Fond Verettes estimate that the floods have affected 10,000 to 20,000 people, either leaving them homeless or destroying their belongings, crops or schools.

"The whole area around Mapou looks like a big lake, and when you look closer you can see all the houses under the water," said Scannell Michel, who flew over Mapou in a helicopter on Thursday. "There are lots of bodies still trapped within the houses and stuck in trees, so there is a very serious health risk there."

U.S. and Canadian military helicopters made about 20 flights to the area on Friday, carrying about 19,000 pounds of rice, beans, soap and other supplies to Fond Verettes and 64,000 pounds of rice, beans, water and cooking oil to Mapou, said U.S. Marine Lt. Col. David Lapan.

The military operation was conducted by the 3,600-member multinational interim force, which was sent to Haiti earlier this year after violence erupted following the resignation of embattled President Jean-Bertrand Aristide.

The military forces evacuated at least three of the injured to Port-au-Prince on Thursday and Friday, Lapan said. Lapan said a 14-year-old boy was evacuated with deep cuts across his neck, shoulders and ears. .

On Friday, the rescuers also flew out a 10-year-old boy, whose mother and seven siblings were killed in the floods. The boy suffered a severe head wound when floodwaters from heavy rains rushed down the deforested hills on Tuesday and blasted through Mapou, a collection of flimsy shacks built in a dry riverbed.

"He had a large patch of flesh missing from the back of his head where he got snagged on some sort of tree limb," said U.S. Marine Lt. Col. Duane Perry, who saw the boy in Mapou before he was airlifted out. "But whatever he got snagged on actually saved his life, because it kept him afloat."

Inigo Alvarez, at the United Nations World Food Program in Haiti, which provided much of the aid airlifted by the military helicopters, said that about 4,000 people who had built homes in the riverbed area were now homeless. He said they required plastic tarps and tents for shelter from rain forecast for the weekend.

"People are desperate. Most have lost relatives, their houses," he said. "Their animals are dead. Their food reserves are gone."

Felipe Donoso, head of the Red Cross in Haiti, said a team that landed in Mapou found seven bodies in its first few minutes.

"The drama is that it is a difficult place to get to, so it is hard to reach the victims," he said.

Donoso said many people who survived the floods had scrambled up hillsides to higher ground, where they remain trapped. The Red Cross said it would use boats to try to reach them on Saturday. Scannell Michel of World Vision said her organization planned to transport a truckload of plastic sheets, blankets, water containers and water-purification tablets on the road toward Mapou on Saturday. She said they hoped to take boats from the point where the roads were blocked.

Haiti, the poorest nation in the Western Hemisphere, is particularly vulnerable to floods and mudslides because of severe deforestation. Poor people around Mapou have cut down many trees for charcoal. Alvarez, of the World Food Program, said about 90 percent of Haitian forests has been wiped out in the last decade.

"It should be stressed, this was heavy rain, not a storm or a hurricane," said Bevan, the U.N. official. "This shows the precarious nature of Haiti." With the tropical storm season still ahead, he said, "there is a lot of reason for pessimism."

Correspondent Mary Jordan in Mexico City contributed to this report.

A woman who lost her parents and brother in the flash floods waits for aid in Jimani in the Dominican Republic.Only rooftops remain above water in the village of Mapou in Haiti. Relief workers said bodies remain in the submerged homes, posing a health risk.