Officials said the violence at the Colonia Agroindustrial prison in the Aparecida de Goiania Complex apparently erupted when inmates from one cellblock invaded three others where prisoners from rival gangs are housed.
The attackers set mattresses on fire when they entered the neighboring corridors and burned the bodies of those who were killed, authorities said. Firefighters were able to contain the fire.
Authorities confirmed the number of dead, but said identifications had not yet been made, G1 reported.
Officers from the Special Penitentiary Operations Group regained control of the prison with the support of military police about two hours after the riot started.
Exactly one year ago, a prison riot at the Anisio Jobim Penitentiary Complex in Amazonas state caused 56 deaths. A day later, four prisoners were killed at the Puraqueuqara Prison Unit in the same state.
Thirty-three more inmates died January 6 in a riot at a prison in Roraima state, and 26 were killed January 14 when inmates rebelled at Alcacuz prison in Rio Grande do Norte.