A number of 52 people have been killed in a prison riot in Brazil between two rival gangs which lasted for five hours, officials say.
A group of Gang members from one prison block invaded another part of Altamira jail in Pará state, local media reported.
Officials giving a news conference said 16 members of the dead were decapitated the remainder suffocated after part of the prison was set on fire.
Two prison officers who were taken hostage have since been freed.
The violence began at around 07:00 local time (10:00 GMT), and ended at around noon, officials said.
Video reported to be from the prison carried by Brazilian media showed smoke billowing from at least one prison building, while another clip appeared to show inmates walking around on the rooftops.
The two rival gangs involved have not been named by authorities.
The prison in Altamira where Monday’s violence broke out has a capacity of 200, but was occupied by some 300 prisoners.
Brazil’s G1 news outlet reported that gang leaders involved in the attack were to be moved to federal prisons for isolation.
Violence in Brazilian prisons is not uncommon.
The country has the world’s third-largest prison population of some 700,000 people, and overcrowding is a widespread problem.