PORTO ALEGRE, Brazil (AFP) — The death toll from floods and mudslides triggered by torrential storms in southern Brazil has climbed to 56 people, with 74 injured and another 67 missing, the country’s civil defense agency said Saturday.

Fast-rising water levels in the state of Rio Grande do Sul were straining dams and threatening the metropolis of Porto Alegre, one of the largest cities in southern Brazil.

Authorities there were scrambling to evacuate some neighborhoods that had been submerged — in some cases using helicopters to rescue people stranded on roofs.

And heavy rains of “very high severity” are expected to continue into Sunday, Civil Defense authorities said.

The rapid rise of the Guaiba River, which runs through Porto Alegre, brought serious flooding to the city’s historic center.

With waters starting to overtop a dike along another local river, the Gravatai, Mayor Sebastiao Malo issued a stern warning on social media platform X, saying, “Communities must leave!”

That warning came a day after the Rio Grande del Sul governor, Eduardo Leite, warned on X that “in the metropolitan region it’s going to be much worse.”

Leite called it the worst disaster in the state’s history.

Residential areas found themselves underwater as far as the eye can see, with roads destroyed and bridges swept away by powerful currents.

Rescuers faced a colossal task, with entire towns — some left without electricity or drinking water — made inaccessible.

At least 300 municipalities have suffered storm damage in Rio Grande do Sul since Monday, according to local officials, displacing more than 24,600.

Roughly a third of the displaced have been brought to shelters set up in sports centers, schools and other facilities.

“When I left the house, I was in water up to my waist,” a haggard-looking Claudio Almiro, 55, told AFP in a cultural center converted to a shelter in a suburb north of Porto Alegre.

“I lost everything.”

The rains also affected the southern state of Santa Catarina, where one man died Friday when his car was swept away by raging floodwaters in the municipality of Ipira.

President Luiz Inacio Lula da Silva visited the region Thursday, vowing “there will be no lack of human or material resources” in responding to the disaster, which he blamed on climate change.

Climatologist Francisco Eliseu Aquino told AFP on Friday that the devastating storms were the result of a “disastrous cocktail” of global warming and the El Nino weather phenomenon.

South America’s largest country has recently experienced a string of extreme weather events, including a cyclone in September that claimed at least 31 lives.

Aquino said the region’s particular geography meant it was often confronted by the effects of tropical and polar air masses colliding — but these events have “intensified due to climate change.”