At least 57 inmates were killed -- including 16 found decapitated -- during a bloody riot between rival criminal factions that erupted Monday morning inside a northern Brazil prison, authorities said.
Para state prison officials said some inmates died of asphyxiation and the death count could rise.
Inmates also set fire to part of the Altamira prison, preventing authorities from accessing parts of the facility. Officials later identified the gangs as the Rio de Janeiro-based Comando Vermelho and a local criminal group known as Comando Classe A.
No members of the prison's staff were injured. Two prison officials were taken hostage during the chaotic fighting but have since been freed, the BBC reported.
The five-hour riot began in the morning and ended around noon, the outlet reported, citing officials.
The deadly uprising is the latest such incident to happen at a Brazilian prison.
In May, nearly 60 inmates were killed at four different prisons in the capital of Brazil’s northern Amazonas state in two days amid riots. At least 40 inmates showed signs of asphyxia in those incidents.
The Associated Press contributed to this report.