BRASILIA: At least 57 people have been killed in a prison riot in Brazil which saw rival gangs battle for five hours, officials say.
Gang members from one prison block invaded another part of Altamira jail in Pará state.
Sixteen of the dead were decapitated and the remainder suffocated after part of the prison was set on fire, officials said at a news conference.
Two prison officers who were taken hostage have since been freed.
Members of the Comando Classe A (CCA) gang set fire to a cell where rival gang members from Comando Vermelho (Red Command) were kept, the Pará state government said in a statement.
The structure of the cell allowed the fire to spread quickly, resulting in the death by asphyxiation of some inmates.
Officials said that the two prison officers taken hostage were soon released, because the goal of the attack was to strike at the rival gang – rather than at the prison guards.
There had been no prior warning or signs of an impending attack on this scale, the statement said.