Firefighters called for the evacuation to higher ground of some 24,000 people from the Brazilian town hit by deadly mud flow from an earlier mining dam rupture, as a second dam threatened to collapse.
Sirens began before dawn on Sunday, triggered by dangerous water levels at a tailings dam still standing in the Vale SA facility near Brumadinho in Minas Gerais state.
The evacuation efforts diverted attention from a search for hundreds of people missing after Friday's dam burst unleashed a torrent of mud, burying the miner's facilities and nearby homes, according to the fire department.
"Our work is completely focused on the evacuation," Pedro Aihara, a spokesman for the state fire department said.
The confirmed death toll rose to 37 bodies found by Sunday morning, the fire department reported.
That already makes the disaster more deadly than a 2015 tailings dam collapse at an iron ore mine less than 100 km (60 miles) to the east, belonging to Samarco Mineracao SA, a Vale joint venture with BHP Group.
That dam break spilled five times the mining waste into a more remote region, burying a small village and contaminating a major river in Brazil's worst environmental disaster on record.
