By Paulo Trevisani and Jeffrey T. Lewis 

BRUMADINHO, Brazil -- Residents of this small, rural Brazilian town, already reeling from the death and devastation left by the collapse of a nearby tailings dam on Friday, were shaken again early Sunday morning when warning sirens and police alerted them that a remaining dam posed a danger as well.

Rescue workers have already recovered 37 corpses from the thick, reddish-brown mud that spewed out of the tailings dam on Friday, and with many people still unaccounted for, authorities fear the number of deaths could rise much higher. Rescue work has been suspended while the area remains on alert due to the danger from the remaining dam.

Warning sirens were activated at about 5:30 am local time Sunday after instruments detected that the water level behind the remaining dam in the iron-ore mining complex had risen, according to Brazilian mining giant Vale SA, owner of the mining operation and of the dams.

Some residents of the area were evacuated as a precaution, with local news organizations reporting that about 24,000 people inhabit the danger zone. Residents were told that the dam, which contains only water, was at risk of collapsing and potentially overflowing the banks of the Paraopeba river.

Francisco Paiva, a 60-year old retiree, said he feared water from the dam could also carry mining rubbish heavy enough to shake the ground and damage the three-store building were he lives and takes care of his 75-year old disabled sister, located at about the Paraopeba's level, some 1,000 feet from the river's west bank.

"The firefighters said the building could be shaken and collapse," he said, standing near the barricade mounted by police to keep people from crossing a bridge over the Paraopeba. Residents have watched the river's water turn red as it has been contaminated by the mining sludge released by Friday's accident.

As with many other Brumadinho residents, Mr. Paiva has done work related to Vale's iron-ore complex. He used to drive a bus taking employees to work and said he always worried about being parked near the imposing tailings dam that collapsed on Friday.

Write to Paulo Trevisani at paulo.trevisani@wsj.com and Jeffrey T. Lewis at jeffrey.lewis@wsj.com

(END) Dow Jones Newswires

January 27, 2019 09:17 ET (14:17 GMT)