Two dam holding back waste water from an iron ore mine burst on Thursday, devastating a nearby town with mudslides and leaving at least two dead and dozens missing.
Residents said no alarms sounded to warn them about the dam break Thursday afternoon, but they scrambled for higher ground after hearing a deafening burst.
Officials have not said what caused the breach, but Guilherme de Sa Meneghin of the state prosecutor's office said there would be a criminal investigation since no warning alarms went off.
The rupture unleashed a mix of water and mining residue on a village four miles downhill, smothering the enclave of Bento Rodrigues. Only about 10 of the village's around 200 houses were left standing, and cars and other objects were tossed by what survivors described as an eruption of mud.
Hundreds of survivors took shelter in the nearby city of Mariana. People slept on mattresses scattered across the floor and picked through piles of donated clothing. Others were sent to area hotels.
The collapse paralyzed operations at the mine, a joint venture between Vale and BHP Billiton , the world's top iron ore miners, and raised fears of an expensive cleanup.
Speaking at a news conference Friday, Meneghin and Minas Gerais state Gov. Fernando Pimentel said the accident was the "biggest natural disaster in the history of our state."
The dam was holding tailings, a mining waste product of metal filings, water and occasionally chemicals. It was located near the Gualaxo do Norte river, adding to fears of potential water contamination, Reuters reported.
. A woman holds an injured dog on Nov. 6.
Rescue work was made difficult by the still wet, quicksand-like mud, according to state fire official Vinicius Teixeira.
"Whoever steps on it runs a great risk of sinking and drowning in this mud," he said, adding that it reached roof-level in some areas. "There is a risk of bodies not being found."