Rescue teams continued searching into the night for hundreds of people missing after a dam collapsed in south-eastern Brazil, as thousands fled another potential breach.

Emergency staff worked past sunset to search for a bus that is thought to have bodies inside and a home where three dead were already discovered, state fire department spokesman Pedro Aihara said.

The collapsed dam at Vale SA’s Corrego do Feijao mine buried mining facilities and nearby homes in the town of Brumadinho in the state of Minas Gerais.

“Until the last body is found, the fire department is acting on the possibility there could be people alive,” Aihara said. “Obviously, given the nature of the accident, as time passes, this chance will go down.”

After announcing the latest number of confirmed dead had risen to 58, civil defence agency spokesman Flavio Godinho told reporters he expected the death toll to continue rising.

Authorities paused the search for survivors for several hours on Monday morning (Australian time) amid fears that a separate dam was at risk of giving way in the area.

At least 3000 people were evacuated from several neighbourhoods in the south-eastern city of Brumadinho, which were within range of the B6 dam, owned by Vale SA.

Firefighter spokesman Pedro Ahiara said the risk of the other dam breaking continued and residents rushed to higher ground.

“With bags on their backs, everything they could grab, children, old people climbing up, it was total despair,” one evacuee told the BBC.

Hope that loved ones had survived a tsunami of iron ore mine waste from the original dam collapse, meanwhile, was fast turning to anguish and anger over the increasing likelihood that many of the hundreds of people missing had died.

Company employees at the mining complex were eating lunch on Friday afternoon local time when the first dam gave way.

By Saturday night, when authorities called off rescue efforts until daybreak, the toll stood at 40 dead with up to 300 people estimated to be missing.

All day Saturday, helicopters flew low over areas encased by a river of mud and mining waste as firefighters dug frantically to get into buried structures.

At least nine people are dead and an estimated 300 people are missing in Brazil after a dam burst at an iron mine in Brumadinho in the southeastern state of Minas Gerais. https://t.co/KfM9wmkM7N pic.twitter.com/lUF6RVQ9pi

— Voice of America (@VOANews) January 26, 2019

Sonia Fatima da Silva, whose son had worked at Vale for 20 years, was trying to get information about him.

“I’m angry. There is no way I can stay calm,” she said.

“My hope is that they be honest. I want news, even if it’s bad.”

Minas Gerais governor Romeu Zema said by now most recovery efforts will entail pulling out bodies.

The flow of waste reached the nearby community of Vila Ferteco and an occupied Vale administrative office.

On Sunday, rooftops poked above an extensive field of the mud, which also cut off roads.

Some residents barely escaped with their lives.

In addition to the 40 bodies recovered by Saturday night, 23 people were admitted to hospital, according to the Minas Gerais fire department.

There had been some signs of hope earlier on Saturday when authorities found 43 more people alive.

The company said that while 100 workers were accounted for, more than 200 were still missing.

Before and after the tailings dam rupture in Brumadinho, Minas Gerais, Brazil.#environment #disaster #brazil #Brumadinho pic.twitter.com/YCU0eve0gV

— Bernardo Cândido (@candidobm) January 25, 2019

Vale chief executive Fabio Schvartsman said he did not know what caused the collapse.

The rivers of mining waste raised fears of widespread environmental contamination and degradation.

Over the weekend, state courts and the justice ministry in Minas Gerais froze about $US1.5 billion ($2.1 billion) from Vale assets for state emergency services and told the company to report on how it would help the victims.

Brazil’s attorney general Raquel Dodge promised to investigate the mining dam collapse.

“Someone is definitely at fault,” she said.

Another dam administered by Vale and Australian mining company BHP Billiton collapsed in 2015 in the city of Mariana, Minas Gerais, resulting in 19 deaths and forcing hundreds from their homes.

Considered the worst environmental disaster in Brazilian history, it left 250,000 people without drinking water and killed thousands of fish.

-with AAP