Ferrying emergency supplies to villagers devastated in deadly floods, U.S. and Canadian troops on Wednesday struggled to assess the scope of a disaster that has killed more than 860 people and left hundreds missing in Haiti and the Dominican Republic.

The death toll has risen steadily since reports began emerging of Monday's disaster. Late Wednesday night, Haitian officials said 200 more bodies had been recovered, bringing the toll there to 450. There have been 417 confirmed deaths in the Dominican Republic.

In addition, several hundred people in both countries were missing.

Dominican authorities told families there was no time to identify many of the bodies because they were badly decomposed and posed health risks if moved. Many bodies were dumped in a mass grave or buried by Dominican soldiers where they were found.

Survivors painted terrifying tales of sleeping families swept away in the floods Monday. Leonardo Novas, a resident of the Dominican border town of Jimani, awoke to the screams of his infant son as water rose in his ramshackle wooden house. He quickly grabbed his wife and his son, and shouted to his brother next door to stay inside. But it was too late.

"Everything's gone -- my house and five family members," said Novas, 28, who had watched helplessly as his brother and his family were carried away in a crushing torrent of mud.

"I can't find them," he said. "I didn't know they were burying them. They should let me find them first."

Jimani is inhabited mostly by Haitian migrants who work as vendors and sugar cane cutters. Dominican officials said some of the Haitians who lost relatives may have been living in the town illegally and may be afraid to come forward to identify bodies.

Troops from a U.S.-led multinational force sent to stabilize Haiti after President Jean-Bertrand Aristide resigned under pressure in February returned to Fond-Verrette, ferrying supplies to about 3,000 villagers and U.N. assessment teams.

After the floods, a landslide covered much of the village with gravel. "For a while we didn't even realize what we were standing on," said Lance Cpl. Justin Collins, one of 20 U.S. Marines who went to help supply villagers with biscuits and fruit. "We were standing on some parts of a neighborhood. It's clear they need more food and water."

The death tolls have been high in Haiti because the impoverished country is nearly 90 percent deforested and many people live in poorly constructed homes.

The Dominican government had issued an alert Sunday, warning that heavy rain might cause rivers to overflow. But Jimani has only limited access to radio broadcasts.

Manie Ceceron, 37, lost her five children in the floods. "The rain came. I was in the house and I ran," she said. "I couldn't see anything. I didn't see my children. I never saw my children."

A Haitian family mourns relatives lost in floods in the town of Fond-Verrette. Mudslides have slowed recovery efforts.