Dozens of helicopters were being used in the operation because the massive gush of mud released by the dam had engulged buildings, vehicles and roads with thick, treacherous sludge. The state fire service leading the efforts said the latest count was 299 people missing, all of them mine workers listed by Vale.
Brazilian President Jair Bolsonaro flew over the devastated zone, but said nothing to reporters in Belo Horizonte when he returned from the flight. He instead took to Twitter to say it was "difficult to not be emotional before this scene." All was being done to care for survivors and "determine the facts, to demand justice and prevent new tragedies," he added.
The military said it was mobilizing 1,000 troops, including sniffer dogs, to the affected zone under orders from Bolsonaro.
The disaster was the first big emergency faced by Bolsonaro and his government since he took office in early January, and perhaps one of the biggest disasters in Brazil's history. The full scope of the damage was still unclear.