At least 52 prisoners have been killed by other inmates in Brazil during a clashes between organised crime groups, officials have said.
Para state prison authorities said 16 victims were decapitated at Altamira prison in northern Brazil, while the others were asphyxiated.
The count could rise when authorities have searched all areas involved, state prisons chief Jarbas Vasconcelos said at a news conference on Monday.
He said a fight broke out at around 7am when breakfast was being served. Inmates also set fires that prevented authorities from entering parts of the facility for about five hours, he said.
The killings echoed those of 55 inmates in a series of riots in May in several prisons in the neighbouring state of Amazonas.
In early 2017, more than 120 inmates died in prisons across several northern states when rival gangs clashed over control of drug-trafficking routes in the region.
The violence lasted several weeks, spreading to various states.
In many of Brazil's prisons, badly outnumbered guards struggle to retain power over an ever-growing population of inmates who run criminal activities from behind bars.
