Officials said at least five of the dead in the riot at Litoral penitentiary in Guayaquil were beheaded.
A state of emergency has been declared in Ecuador’s prison system, after more than 100 people died in a battle among gang members in a coastal prison.
The country’s president Guillermo Lasso declared the emergency on Wednesday, the day after the riot at the Litoral penitentiary in Guayaquil - giving the government powers that include deploying police and soldiers inside prisons.
At least 116 people died, and 80 were injured in the violence. Officials said at least five of the dead were found to have been beheaded.
It was the worst prison bloodbath the country has seen.
Officials blamed the violence on gangs linked to international drug cartels fighting for control of the facility.
Warning he could not guarantee that authorities had regained control of the lockup, Lasso said: “It is regrettable that the prisons are being turned into territories for power disputes by criminal gangs.”
Images circulating on social media showed dozens of bodies in the prison’s Pavilions 9 and 10 and scenes that looked like battlefields.
The fighting was with firearms, knives and bombs, officials said. Earlier, regional police commander Fausto Buenaño had said that bodies were being found in the prison’s pipelines.
Outside the prison morgue, the relatives of inmates wept, with some describing to reporters the cruelty with which their loved ones were killed, decapitated and dismembered.
“In the history of the country, there has not been an incident similar or close to this one,” said Ledy Zúñiga, the former president of Ecuador's National Rehabilitation Council.
Zúñiga, who was also the country's minister of justice in 2016, said she regretted that steps had not been taken to prevent another massacre following deadly prison riots last February.
Earlier, officials said the violence erupted from a dispute between the “Los Lobos” and “Los Choneros” prison gangs.
In July, the president decreed another state of emergency in Ecuador’s prison system following several violent episodes that resulted in more than 100 inmates being killed.
Those deaths occurred in various prisons and not in a single facility like Tuesday's massacre.
Previously, the bloodiest day occurred in February, when 79 prisoners died in simultaneous riots in three prisons in the country.
In July, 22 more prisoners lost their lives in the Litoral penitentiary, while in September a penitentiary center was attacked by drones leaving no fatalities.