Nine inmates in a prison in Brazil died and 14 were injured on Monday as rival gangs clashed, AP reported. The incident occurred at the Colonia Agroindustrial prison in the central Brazilian state of Goias.

Jorimar Bastos, the head of the prison warders association in Goias, said that only five prison officers were on duty when inmates from one cellblock went into three other cellblocks where prisoners from rival gangs were housed. The prisoners set mattresses on fire and burned the bodies of those they killed, authorities said. One of the inmates was decapitated, BBC reported.

About 106 inmates escaped during the riot, the O Estado de Sao Paulo newspaper reported. Officials said they had recaptured 29 prisoners while the others remained at large. “It was a clash between prisoners and it is all under control now,” said Lieutenant-Colonel Hrillner Braga Ananias.

In January 2017, at least 56 inmates at a prison complex in Brazil’s Amazonas state were killed during a riot caused by rival drug gangs. Brazil’s penitentiary system has frequently been criticised by rights groups for overcrowding and excessive violence. “Our prisons were built to annihilate, torture and kill,” the director of Pastoral Carceraria, a Catholic centre monitoring prison conditions, had said.