Teresopolis , Brazil ( CNN ) -- The death toll from flooding caused by torrential rains in Brazil 's Rio de Janeiro state rose to 591 people Saturday , Brazil 's official news agency reported . Most of the deaths were reported in the cities of Nova Friburgo and Teresopolis , located in a mountainous region northeast of Rio , according to Agencia Brasil . Rescuers have not been able to reach some hard-hit areas and many more people are feared dead , the agency said Friday . The rain is predicted to continue for several days in areas already submerged in water or slathered with mud . Thousands of families are still living on mountain slopes or on riverbanks and face extreme risk of being washed away . One resident described the disaster as a tsunami that fell from the sky . Chaos reigned in the especially hard-hit city of Teresopolis , where some residents donned masks and helped clean streets or deliver first aid . Others combed the city , searching desperately for missing loved ones . Schools and police stations turned into overflowing morgues , where people waited to identify their family and friends . Municipal worker Reginald de Oliveira came to see if he could find the body of his uncle , missing in the floods . He was trying to save his family when a wall of water washed him away . Red Cross volunteer Maria Helena de Jesus was helping with first aid . `` You have to almost have a heart of stone , '' she said . `` It was very difficult . '' Teresopolis Mayor Jorge Mario Sedlacek declared his city a natural disaster area . At least 257 people died in Teresopolis , while 267 were killed in the town of Nova Friburgo , Agencia Brasil reported . President Dilma Rousseff flew over flood-affected areas Thursday and landed in a slushy , trash-littered soccer field in Friburgo , the agency said . The floods are her first test as president . She trudged through mud in her rain boots to talk to residents in a neighborhood where four of seven firefighters attempting to rescue people had been buried under mud . Three others were pulled out alive . `` We are going to take firm action , '' to help the devastated areas , said Rousseff , who assumed office at the first of the year . Brazilian authorities have been criticized for a lack of disaster planning and allowing people to build homes in areas known to become treacherous in the rainy season . They are under increasing pressure to show a strong response . Brazil is scheduled to host the World Cup in 2014 and the Olympics in 2016 . With more rain forecast , Brazilian authorities have ordered evacuations for at least 5,000 families living in especially perilous areas in Rio de Janeiro state , Agencia Brasil said . Another 3,000 families from a mountainous region were homeless and sheltered in schools and gymnasiums , the news agency said . `` The most important thing right now is to assist the homeless population and reach the most critical points , '' said Rodrigo Neves , the state secretary of Social Welfare and Human Rights . State health officials pleaded for people to donate blood that will be sent to the Serrana region , where only 36 units of blood remained for treatment of flood victims . Rain has affected neighboring Sao Paulo as well , killing 24 people there , authorities said . Journalists Fabiana Frayssinet and Helena DeMoura contributed to this report .
Most of the deaths occurred in hard-hit cities of Teresopolis and Nova Friburgo . Officials fear more may be dead in the flooding in Rio de Janeiro state . Rain is predicted to continue for several days .