The toll in the Brazil dam collapse rose to 40 on Saturday as rescuers braved rains to look for bodies in the deep mud, AP reported. An estimated 300 people are still missing and authorities expect the toll to rise.

The dam at an iron ore mine in the state of Minas Gerais was holding back waste. It collapsed on Friday, flooding the town of Brumadinho and its vicinity in a torrent of slush. The mine is owned by Vale SA and the disaster has been described as the second major incident involving the company in the past three years. As scores of families in the city desperately waited for news about their loved ones, Minas Gerais’s Governor Romeu Zema promised that those responsible “would be punished.”

“I saw all the mud coming down the hill, snapping the trees as it descended,” said 45-year-old Simone Pedrosa, a resident of Parque Cachoeira, which is about 8 km from where the dam collapsed. “It was a tremendous noise.” Pedrosa and her parents drove to the highest point in the neighborhood to escape the slush. “If we had gone down the other direction, we would have died,” she added.

Vale CEO Fabio Schvartsman said he did not know what caused the collapse. About 300 employees were working when the incident occurred. Emergency workers suspended their search shortly after nightfall and plan to resume at first light on Sunday morning.

Brazilian environmental agency Ibama has slapped a 250 million reais (Rs 469 crore) fine on Vale for violations related to the tragedy, The Guardian reported. The company has caused pollution, turned the area unfit for habitation and committed other regulatory violations, Ibama added.

Brazil President Jair Bolsonaro visited Minas Gerais on Saturday and flew over the disaster area. “We will do what is within our reach to attend the victims, minimise damages, investigate the facts, demand justice and prevent new tragedies like Mariana and Brumadinho,” he tweeted.