At least 116 people are now known to have died in a fight between rival gangs in Ecuador's jail, officials say, making it the worst prison violence in the country's history.
At least five inmates were decapitated in Tuesday's clashes in the city of Guayaquil, while others were shot dead.
The Litoral Penitentiary houses inmates from Ecuadorean gangs thought to have links to Mexican drugs cartels.
It is considered one of the most dangerous prisons in the country.
Police commander Fausto Buenaño says the prisoners also threw grenades. It took 400 police officers to regain control.
Local media report that the uprising was ordered by powerful Mexican drug trafficking gangs that are now operating in Ecuador.