Flooding following a cyclone in southern Brazil has washed away houses, trapped motorists in vehicles and swamped streets in several cities, killing at least 31 people and leaving 2,300 homeless.

More than 60 cities have been battered since Monday night by the storm, which has been Rio Grande do Sul state’s deadliest, Governor Eduardo Leite said.

“The fly-over we just did, shows the dimension of an absolutely out of the ordinary event,” Leite said in a video posted on the state’s social media accounts. “It wasn’t just riverside communities that were hit, but entire cities that were completely compromised.”

Videos shot by rescue teams on Tuesday had shown some families on the top of their houses pleading for help as rivers overflowed their banks. Some areas were entirely cut off after wide avenues turned into fast-moving rivers.

In Mucum, a city of about 50,000 residents, rescuers found 15 bodies in a single house. Once the storm had passed, residents discovered a trail of destruction along the river with most buildings swept away down to the ground level. Images showed a sheep hanging from an electrical line – an indication of how high the water had risen.

“The water arrived very fast, it was rising two metres (6.5 feet) an hour,” Mucum resident Marcos Antonio Gomes said, standing on top of a pile of debris. “We have nothing left. Not even clothes.”