MARIANA, Brazil — The death toll from two collapsed dams at a major Brazilian mine will surely rise in coming days, a local mayor said on Saturday, while search and rescue teams worked to reach villages more than 50 miles downstream overrun by the massive mudflow.

Twelve residents of the nearest village 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 list of 19 missing people on Saturday, including three children, ages 4 to 7, and a 60-year-old woman from the village, which was swamped by mudslides within half an hour of public warnings.

PHOTOS: Mud Engulfs Brazilian Village after Dams Collapse

The mine's operator, Samarco, is co-owned by the world's largest mining company BHP Billiton Ltd and the biggest iron ore miner Vale SA. Clean-up and repairs along miles of flooded river could cost the companies a fortune.

Walls of water filled with mining waste cascaded downhill when the dams burst 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.

Men take out a bag from a house flooded with mud after a dam in Barra Longa, Brazil, on Nov. 7, 2015. RICARDO MORAES / Reuters

"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.