The violence is linked to a planned transfer of prisoners to a new high-security prison in another province.
The incident comes barely two months after 14 inmates died in the same prison, according to authorities, during clashes between rival gangs.
Previously relatively safe Ecuador has in recent years been hit by a severe wave of violence linked to organized crime, and the country's prison system has problems with overcrowding.
Since 2021, over 500 people have been killed in prison violence in Ecuador.
