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Brazilian firemen rescue a foal in Mariana, Minas Gerais state, Friday, Nov. 6, 2015, after two dams burst the previous day. Getty Images

The number of dead and missing from the dam collapse in Brazil remained unclear Saturday as emergency workers struggled to help villagers recover after two dams burst in Minas Gerais state. Reuters reported one person had been confirmed dead and 25 had vanished, though Brazilian paper O Tempo cited a source saying 10 were dead and 30 were missing.

"The death toll will rise for sure," Mariana Mayor Duarte Júnior told Reuters. At least three of the people missing were children, and one woman was as old as 60. "Some people still aren't accounted for."

Two dams in Minas Gerais broke unexpectedly Thursday, sending 62 million cubic meters of water and mud flooding the towns of Bento Rodrigues, Barra Longa and Mariana. The dam facility, run by the Samarco mining company, did not have a warning siren. "When I went outside, there were already people running uphill saying the dam burst," resident Joaquim Teofilo Dutra told the Associated Press. "All I did was close my house and run to the top."

Rescue efforts by at least 400 firefighters, police and military extended through Saturday but were complicated by surging rivers and rainstorms. O Tempo reported that some residents were refusing to leave their houses and animals, even though the villages had no power or drinking water.

"Whoever steps on it runs a great risk of sinking and drowning in this mud," the AP reported firefighter Vinicius Teixeira told newspaper O Globo. "There is a risk of bodies not being found."

Samarco representatives wrote on Facebook that the mud itself is likely not toxic. Operations at the dam facilities have been halted. "The mining company is mobilizing every effort to prioritize the care and integrity of the people who were working in or living near the dams in addition to actions to curb environmental damage," Samarco said.