Bodies were thrown over the wall of the complex, and at least six people were decapitated, the news agency reported.
The revolt started Sunday afternoon as part of a rivalry between two criminal organizations at the Anisio Jobim Prison Complex in the city of Manaus, Agencia Brasil reported, citing Sergio Fontes, the public safety secretary for the state of Amazonas.
Violence erupted on Sunday between incarcerated members of the the Familia do Norte (FDN) and the Primeiro Comando da Capital (PCC) groups. The riot lasted for more than 17 hours.
The FDN controls drug trafficking and the "inside of prison complexes," according to state media. Fontes said that the riot started over control of the drug trade behind the prison walls.
"They weren't fighting because one is called one thing and the other one is called another. They are fighting for money," he said.
"There is a silent war going on, and the state must intervene. What is this war? Drug trafficking. What did we see today? One faction fighting with another."
Among the hostages were 74 prisoners and an unknown number of prison guards, Fontes said. Authorities said they did not know how many prisoners might have escaped from the complex.
Separate prison break
As the riot raged, "dozens" of prisoners orchestrated an escape from another Manaus prison, the Antonio Trindade Penal Institute (Ipat). Fontes speculated that the jailbreak could have been arranged as a "smokescreen" for the Anisio Jobim riot, according to the Agencia Brasil report.
Prisoners also caused a "commotion" at one other penitentiary, according to the Amazonas public security secretariat.
Security forces did not enter the Anisio Jobim complex due to the "unpredictable" nature of the situation. According to Fontes, the riot "was managed with negotiation and respect for the human rights."
He said said the riot instigators will be identified and held accountable for the murders and other crimes.
Extra funding requested
Alexandre de Moraes, Brazil's justice minister, told reporters on Monday evening in Manaus, that the gang members responsible for the riot will be transferred to federal prisons.
"This is an important step to identify and remove those that headed this absurd riot on the first of the year," he said.
Following the New Year's incident, the government of the state of Amazonas has called for federal support to combat drug trafficking and strengthen security in Brazil's detention centers.
Fontes said the preliminary investigation suggests the riot was premeditated.
"Everything indicates that the acts were planned over a long period of time," he said.
"The inmates had established with the administration (of the prison) a promise that everything would run smoothly throughout the holidays and there wouldn't be any problems. They didn't keep their promise, but you can't expect much from criminals, can you?"
The number of prisoners killed in Sunday's incident is the highest since the deadly 1992 Carandiru massacre. In that case, 111 inmates died after police stormed the Carandiru penitentiary following a riot.