MARIANA, Brazil (Reuters) - Rescue teams on Saturday struggled to reach villages devastated by a massive mudflow after two dams burst at a major Brazilian mine, wreaking havoc more than 80 km (50 miles) downstream and prompting officials to warn of a higher death toll.
A dozen residents of nearby villages remain missing, along with 13 workers from the mine, but only one death has been confirmed in what the governor of mineral-rich Minas Gerais described as the state's worst environmental disaster.
"The death toll will rise for sure ... The number of missing will rise because we're talking to the residents of Bento (Rodrigues) and some people still aren't accounted for," Duarte Júnior, mayor of the nearby city of Mariana, told reporters.
City officials released a partial list of missing people, including three children, ages 4 to 7, and a 60-year-old woman from the village, which was swamped by mudslides within a half hour of public warnings.
The mine's operator, Samarco, is co-owned by the world's largest mining company BHP Billiton Ltd (BHP.AX)(BHP.N)(BLT.L) and the biggest iron ore miner Vale SA (VALE5.SA)(VALE.N). Clean-up and repairs along miles of flooded river could cost the companies a fortune.
A state public prosecutor based in Mariana said on Saturday he will seek 500,000 Brazilian reais ($130,000) in personal damages for each of about 200 families most affected by the dam burst.
While it is still unclear what caused the collapses, Samarco said Saturday that workers were doing normal scheduled work on one of the dams to increase its size when it burst, sweeping them away in the flood.
Walls of water filled with mining waste cascaded downhill when the dams broke on Thursday, engulfing the village of Bento Rodrigues and its 600 residents in a sea of mud while also flooding others far removed from the open-pit mine.
"They didn't tell us the mud would come through with such force," said Losangeles Freitas, resident of Barra Longa, a town nearly 80 kilometers downstream flooded by the 60 million cubic meters of waste water and mud.
"We lost everything. It moved so fast," she said.
Her neighbor Bernardo Trinidade, a 58-year-old plumber, said authorities warned that the river behind his house would swell by a meter or two. But the waters rose more than 10 meters, he said, sweeping into his home at 3 a.m. - nearly half a day after the dam broke.
"We took what we could and ran upstairs," said Trinidade. "We were told it wouldn't be so bad."
Half a dozen jeeps with water and emergency supplies rolled through Barra Longa on their way to Gesteira, one of several remote villages along the river that rescuers had not yet reached.
As rescue teams labored to reach isolated communities, state officials were taking precautions to contain the environmental fallout from the burst dams.
The dams held back so-called tailings ponds, masses of finely ground waste rock and water left over from extracting more valuable minerals, which can contain harmful chemicals.
Civil defense officials said state sanitation authorities would test the toxicity of the rivers. In the meantime residents who came in contact with the thick mud were advised to shower and dispose of their clothing.
Samarco sought to play down those fears, saying there were no chemical elements in the tailings dams that posed health risks when the accident occurred.
Samarco's chief executive said the mine's environmental licenses were up to date and the dams had been inspected in July.
Executives have said a tremor in the vicinity of the mine may have caused the dams to burst, but that it was too early to establish the exact cause.
Samarco said it had set no date to restart the mine, which produces about 30 million tons of iron ore annually. Output is shipped to Brazil's coast and converted into pellets for export to steel mills.
The cleanup bill and potential environmental lawsuits could be more costly than the loss of output. BHP Billiton and Vale already face iron ore prices at their lowest in a decade.
($1 = 3.7698 Brazilian reais)
Additional reporting by Alonso Soto in Brasilia; Writing by Brad Haynes; Editing by Jason Neely and Mary Milliken