President Luiz Inacio Lula da Silva arrived in Rio Grande do Sul on Sunday morning with most members of his cabinet to discuss rescue and reconstruction works with local authorities.
"Bureaucracy will not stand in our way, stopping us from recovering the state's greatness," Lula said at a press conference.
"It is a war scenario, and will need post-war measures," state governor Eduardo Leite added.
The death toll could still substantially increase as 105 people were reported missing on Sunday, up from about 70 the prior day, according to the state civil defence authority. It also said it was investigating whether another four deaths were related to the storms.
Flooding from storms in the past few days has affected more than two thirds of the nearly 500 cities in the state, which borders Uruguay and Argentina, leaving more than 115,000 people displaced, according to authorities.
Floods have destroyed roads and bridges in several cities. The rains also triggered landslides and the partial collapse of a dam at a small hydroelectric power plant.
More than 400,000 people were without power on Sunday evening, while nearly a third of the state's population was without water, authorities said.
In Porto Alegre, the state capital, the Guaiba lake breached its banks, hitting the highest water level on records, according to the national geological service. Porto Alegre's international airport has suspended all flights since Friday.
In the city of Canoas near Porto Alegre, Julio Manichesque, 76, was rescued by volunteers after he had stayed since Friday on the roof of the house where he has lived for 52 years.
"I have never seen that much water," Manichesque said.
Many volunteers also have been risking their own safety during the rescue efforts, using small boats, jet skis and kayaks.
Fabiano Saldanha, 30, said he and three friends have used jet skis to rescue about 50 people since Friday in islands that are part of Porto Alegre.
"The only thing we hear when we enter a street is 'help,' 'help'," Saldanha said.
During his weekly address to crowds in St. Peter's Square in Vatican City, Pope Francis said on Sunday he was praying for the people of the state.
"May the Lord receive the dead, comfort their families and all those who had to leave their homes," the pope said.
