At least eight prisoners were asphyxiated in a fire during a battle between rival gangs in a Brazilian prison Monday, bringing to 33 the number of dead in two separate prisons in less than 24 hours, according to media reports.
Police believe the riot at the prison in the northern city of Porto Velho was tied to one at a separate prison the day before, where 25 people died, including seven decapitated and six burned to death.
The violence Sunday at a prison in the remote northern city of Boa Vista - 1,600 kilometres from the Porto Velho prison - broke out during visiting hours, when a group of prisoners broke into another wing of the jail armed with knives and wooden poles.
Around 100 of the Boa Vista inmates' relatives, mainly women, were also temporarily taken hostage by prisoners who demanded to speak to a representative of the judicial authorities.
They were later freed by a security task force.
The fighting pitted members of the First Capital Command (PCC) crime group against the smaller Red Command (CV).
The country's largest criminal organization, the PCC is based in Sao Paulo, while the CV controls territory in Rio de Janeiro.
Brazil has one of the largest prison populations in the world. Prisons are often under the control of organized crime groups, rather than authorities. Conditions are poor, with rampant overcrowding, and riots are not uncommon.
Brazil Justice Minister Jose Eduardo Cardozo last year described the country's prisons as "authentic schools of crime."