Flooding was largely centered on the coastal state of Espirito Santo, the Brazilian newspaper O Globo reported Tuesday.
Ongoing rains in the region caused the death of two women and a child Tuesday in a landslide in the state's mountainous region, one of the areas hardest hit by the storms.
Civil defense officials said at least 77 cities in neighboring Minas Gerais state also had been flooded.
Some 3,400 people in that state have been displaced from their homes. More than 700 people are homeless.
President Dilma Rousseff flew over the area for 40 minutes Tuesday and later met with Espirito Santo Gov. Renato Casagrande. She described the extent of flooding was "absurd."
The governor said rain had fallen in the state for seven straight days. The area received 0.4-inches of rain Monday, he said.
"We have never had such an intense rain," he added.
Helena Chagas, secretary for social communication, said the government was providing 12,000 food hygiene and sanitation kits to residents of the affected areas, as well as 20,000 water purification pills.
Military helicopters and trucks have been sent into the area, Chagas said, along with 80 members of the National Security Force. Four geologists will help identify risk areas.
Temporary bridges will be built to enable aid to reach the flooded areas.
Audifax Barcellos, the mayor of Serra, one of the most affected cities, placed damage estimates at $50 million. He said some 15,000 people in the city had been forced from their homes by high water. Some 1,500 were being housed in shelters.
Some 600 securities and fire personnel were working to rescue victims in affected areas.