A dam collapse at an iron-ore mine in southeast Brazil has left at least seven people dead and some 150 others missing, officials say.
The break caused a sea of muddy sludge to spread across rural areas of Brumadinho, in Minas Gerais state, burying buildings and vehicles.
Emergency teams rescued scores of trapped people by helicopter.
The accident comes just over three years since a dam burst in another town in Minas Gerais, killing 19 people.
Many of the missing are workers who were having lunch in the dam's cafeteria which was buried by the sludge.
It is not clear what caused the dam - owned by Brazil's largest mining company, Vale - to break.
What do we know so far?
The dam near Feijão iron ore mine burst its barrier at around lunchtime local time on Friday, flooding another dam down below.
Built in 1976, the dam was one of several in the area and it was used to hold residue from the mine.
It had capacity for 12m cubic metres and had been an inactive site for three years, according to Vale. It is not yet known how much waste was released.
Leaked tailings from the mine spread into the nearby community of Vila Forteco, close to Brumadinho.
Residents in low-lying areas have been evacuated, many of them by helicopter.
"We do not have more details because everything is happening very fast," Brumadinho Mayor Avimar de Melo said.
"Our main worry now is to quickly find out where the missing people are," he told television channel GloboNews.
Some 100 rescuers are searching for the missing with 100 more expected to join them on Saturday.
On Twitter, President Jair Bolsonaro called it a "serious tragedy" and said he would visit the region on Saturday.
The ministers for the environment, mines and energy, and regional development were travelling to the scene.
What does the company say?
Vale chief executive Fabio Schvartsman called it an "enormous tragedy".
He said a German company had been hired to assess the dam and that the last report from September indicated that it was stable.
Some 300 Vale employees were in the area at the time of the accident and 100 have been accounted for so far, he added.
The firm has said it was monitoring all its other dams for any risk of collapse.
Has this ever happened before?
On 5 November 2015, a dam - also owned by Vale, along with BHP Billiton - burst at a Samarco mine in Mariana, in Minas Gerais.
More than 60m cubic metres - enough to fill 20,000 Olympic swimming pools - spilled over into the surrounding area.
The incident is considered Brazil's worst environmental disaster.
After a lengthy court case, BHP Billiton and Vale reached a settlement worth at least 6.8bn reais ($1.8bn) with the Brazilian government.
Source: BBC News
BDST: 1017 HRS, JAN 26, 2019
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