BRASILIA/RIO DE JANEIRO (Reuters) – Brazilian rescuers were searching for some 200 missing people after a tailings dam burst on Friday at an iron ore mine owned by Vale SA, with seven bodies recovered but the death toll expected to rise sharply.

Avimar de Melo Barcelos, the mayor of the town of Brumadinho where the dam burst in Brazil’s mining hub of Minas Gerais state, said seven bodies had been recovered by nightfall.

However, Vale Chief Executive Fabio Schvartsman said only one-third of the roughly 300 workers at the site of the disaster had been accounted for. He said a torrent of sludge tore through the mine’s offices, including a cafeteria during lunchtime.

U.S.-listed shares of Vale tumbled as much as 10 percent after the incident, the second major disaster at a Brazilian tailings dam involving Vale in just over three years.

Both hit Minas Gerais, which is still recovering from the collapse of a larger dam in November 2015 that killed 19 people. That dam, owned by a joint venture between Vale and BHP Billiton called Samarco Mineracao SA, buried a nearby village and devastated a major river with toxic waste in Brazil’s worst environmental disaster.

Operations at Samarco remain halted over legal disputes relating to damages even after the companies settled a $5.28 billion civil lawsuit last year.

Schvartsman said the dam that burst on Friday at the Feijao iron mine was being decommissioned and had a capacity of 12 million cubic meters – a fraction of the roughly 60 million cubic meters of toxic waste released by the Samarco dam break.

“The environmental impact should be much less, but the human tragedy is horrible,” he told journalists at Vale’s offices in Rio de Janeiro. He said equipment had shown the dam was stable on Jan. 10 and it was too soon to say why it collapsed.

Fire brigade spokesman Lieutenant Pedro Aihara said the torrent of mud stopped just short of the local Paraopeba river, a tributary of Brazil’s longest river, the Sao Francisco.

“Our main worry now is to quickly find out where the missing people are,” Aihara said on GloboNews cable television channel. Scores of people were trapped in nearby areas flooded by the river of sludge released by the dam failure.

Helicopters plucked people covered in mud from the disaster area, including a woman with a fractured hip who was among eight injured people taken to hospital, officials said.

The Feijao mine is one of four in Vale’s Paraoeba complex, which includes two processing plants and produced 26 million tonnes of iron ore in 2017, or about 7 percent of Vale’s total output, according to information on the company’s website.

Feijao alone produced 7.8 million tonnes of ore in 2017.