New Delhi: At least 25 inmates were killed on Sunday in clashes between rival criminal factions at a prison in northern Brazil, local media reported.

Seven of the dead were beheaded and six were decapitated and burned to death in a fight at Prison Farm of Monte Cristo in Boa Vista, the capital of Roraima state, the news site G1 reported, citing local police. The inmates of one wing broke into another wing.

The incident happened during visiting hours and some 100 relatives of the inmates were held hostage.

“They were armed with knives and wooden clubs,” said an inmate’s wife who was in the prison when the clashes broke out.

The rioters demanded that a judge come to hear their demands.

All the hostages were released later by the police.

Riots and clashes are very frequent in the overcrowded prisons of Brazil.

The head of the union of Roraima penal workers, Joana Moura, told the Folha de Boa Vista newspaper that the incident was “a reflection of the lack of interest from the state government” towards the prison system. According to Moura, “there is no security equipment, there are not enough personnel for the tasks, and the agents are working beyond their limits”.