Rescue workers in northeast Brazil were Friday searching for three missing people after heavy rains broke open a dam, releasing a torrent of water that killed five people and destroyed 500 homes.

It was a "miracle" more people did not die, a spokeswoman for the Piaui state government which was coping with the disaster told AFP.

"The search resumed at dawn. Firemen found a new body, which brought the number of victims to five. But, out of 11 people given as missing, eight have been found alive," she said.

The dam burst on Thursday after days of heavy rain, sending forth 52 million tons of water that swept up everything in its path: houses, trees, cattle. It flooded part of the town of Cocal da Estacao, where 30,000 people live.

"I've only seen that once before, in a film," one resident told the Globo television network after seeing his five goats and two cows taken by the torrid flood.

State officials said washed out roads were making rescue operations difficult, and they feared the death toll could rise. Nearly 3,000 people were left homeless, they said.

More than 100 police and firemen were working in the area, plying the Pirangi river by boat while five helicopters flew overhead.

Heavy rains, provoking flooding and mud-slides, have been lashing Brazil's normally semi-arid northeast for several weeks. A total of around 60 people have died.