Up to 40 people have been killed in a riot in a Brazilian prison in a remote Amazon town.
Police are preparing to storm the facility. Local media reports said the Porto Velho prison in the Amazon state of Rondonia has 900 inmates in 60 cells.
Some 300 detainees launched a riot in protest at overcrowding at the facility, and at new rules restricting their movement inside it.
"We know there are dead but we cannot confirm how many, it could reach 40," said Mr Jose Mario Alves, a military police official.
Mr Alves said the rebellion was suspected to have started when there was a confrontation between armed prisoners.
"We suspected that something was going to happen, there was tension," he said.
Prison rebellions are widespread in Brazil, mainly due to cramped conditions. Rioting by 20,000 inmates in 29 jails across Sao Paulo state at the beginning of last year killed 19 prisoners.