Heavy rains in southern Brazil have killed 37 people, local authorities have said, with dozens still unaccounted for.
More than 70 people are missing and at least 23,000 people have been displaced in Rio Grande do Sul, according to the state’s civil defence agency.
In some cities, water levels have been at their highest since records began almost 150 years ago, the Brazilian Geological Service said.
It said the flooding is the worst to hit the state in more than 80 years, surpassing that of a historic deluge in 1941.
Roads have been turned into rivers in several towns, with bridges destroyed and the storm triggering landslides and the partial collapse of a dam structure at a hydroelectric power plant.
Residents near to a second dam in the city of Bento Goncalves have been ordered to evacuate, as fears of another collapse grow.
“It’s not just another critical situation, it’s probably the most critical case the state has ever recorded,” Rio Grande do Sul Governor Eduardo Leite said on social media.
He added the number of deaths will likely rise as authorities have not been able to reach some locations.
President Luiz Inacio Lula da Silva has travelled to the state to visit affected locations and discuss rescue efforts with the governor.
The state is at a geographical meeting point between tropical and polar atmospheres, which has created periods of intense rains and others of drought.
Scientists believe the pattern has been intensifying due to climate change.
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Heavy rains hit the state last September, as an extratropical cyclone caused floods that killed more than 50 people.
That came after more than two years of a persistent drought due to the La Nina phenomenon.
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