At least 537 people have been killed and many more are feared dead after floods and landslides devastated towns and villages in a mountainous area near Rio de Janeiro.
Renewed rainfall on Friday threatened to complicate efforts by rescue teams to reach survivors trapped in isolated areas.
Rivers of mud tore through towns in the mountainous Serrana region, levelling houses, throwing cars atop buildings and leaving thousands of people seeking shelter.
"The rain did not stop at dawn and is continuing in the morning, which is making the rescue efforts more difficult," Lieutenant Rubens Placido, a fireman in the hard-hit town of Nova Friburgo, said.
"The number of deaths is going to rise quite a bit. There are still a lot of people buried."
At least 223 people are believed to have died of the town of Teresopolis, where hundreds more are feared buried under the rubble of their homes after the equivalent of a month's rain fell in less than 24 hours.
"There are three or four neighbourhoods that were totally destroyed in rural areas," Jorge Mario, the mayor of Teresopolis, said. "There are hardly any houses standing there and all the roads and bridges are destroyed."
Television images of the three towns hit by the torrents of water and mud showed emergency workers going through the ruins of collapsed homes in a search for survivors, but often finding only bodies.
Al Jazeera's Gabriel Elizondo, reporting from Teresopolis, said the makeshift morgue set up at the city's main police station was overflowing with bodies.
"They literally don't have any more room for bodies and they are thinking about sending corpses to the main football stadium in town. That gives you an idea of the gravity of the situation they are facing," he said. (they are putting them in refrigerated trucks)
"I was in some of the most affected areas today ... and they were literally pulling out dozens of bodies while I was there.
"Clearly the death toll is, no question, going to go up because this is clearly shaping up to be one of the worst natural disasters Brazil has ever faced."
Survivors recounted the horrors of watching homes swept away by walls of earth and water and of frantic efforts to dig with bare hands to reach trapped neighbours.
"We were like zombies, covered in mud, in the dark, digging and digging," Geisa Carvalho, a local resident, told the Associated Press news agency.
Geisa and her mother Vania Ramos were awoken by a loud rumble as tonnes of earth slid down a sheer rock face onto their neighbourhood.
"I don't even have the words to describe what I've seen," Ramos said.
"A lot of our friends are dead or missing. There are people we may never find."
More than 13,500 people have been left homeless after the surging waters toppled their houses.
"Most of them are going to stay with friends of family ... but [officials] are trying to set up tent cities here now in the next two to three days for people who need that," our correspondent said.
Supplies running short
Residents said they had no food, water or medication, and many made the long walk to the main area of Teresopolis to get help.
The effect on other remote communities is still to be established as destroyed roads have made it impossible for rescue operations to reach them.
The government said it was sending 210 troops from the National Public Security Force, including officials to help identify bodies.
Two navy helicopters were assisting rescue operations and the navy was also sending a mobile field hospital to the area.
Dilma Rousseff, Brazil's president, called the situation a tragedy after flying over the scene.
"Housing in areas of risk is the rule in Brazil rather than the exception," she said after visiting Nova Friburgo, where much of the damage was done to homes built precariously at the base of steep hills.
"When there aren't housing policies, where are people who earn no more than twice the minimum wage going to live?"
Rouseff signed a measure on Wednesday sending $461m to towns in Rio and Sao Paulo states that were damaged during the rains. The money will go towards repairing infrastructure and preventing future disasters.
Heavy rains, common during Brazil's summer wet season, were intensified this week by a cold front which doubled the usual precipitation.
+ Photos. WARNING for bodies!
"The most beautiful sight of Nova Friburgo", not so beautiful anymore.
Hurt horse trapped under debris.
Some rescuers didn't escape.
Sérgio Cabral, Governor of Rio (left) and Brazil's President Dilma Rousseff (center) visited the area.
Al Jazeera's video (part of the article):
Click here for some before/after pics.