Video obtained by Reuters showed rising water flooding streets and rivers and submerging houses in the small town of Mucum, in Rio Grande do Sul state. Nearby cities such as Lajeado and Roca Sales were also hit severely.
Dominguez Fontana, a 74-year-old sawmill worker who escaped the Mucum flooding, said nothing could be salvaged, Reuters reported.
"When the water was coming I escaped to the highway," he explained. "You have to escape. If you stay there you die."
Rain stopped on Tuesday but weather forecaster Climatempo forecast more on Wednesday and Thursday before showers dissipate by Sunday, with the state still on alert for floods.
The Rio Grande do Sul floods are just the latest recent natural disasters in Brazil. More than 50 people were killed in Sao Paulo state this year after massive downpours caused landslides and flooding.
The colonial-era city of Petropolis near Rio de Janeiro and Bahia state has suffered similar disasters, as well as Santa Catarina, a state neighboring Rio Grande do Sul where an additional victim was confirmed on Tuesday.
President Luiz Inacio Lula da Silva said he had spoken to Rio Grande do Sul Governor Eduardo Leite to offer the federal government's full support.
Lula sent two ministers to oversee search and rescue efforts and said Vice President Geraldo Alckmin would also be "on standby" to travel to the hard-hit Rio Grande do Sul state, home to about 11 million people.
SKH/PR