Gunfire as rival gangs battled it out inside Cadereyta prison in northern Mexico.
Guards were taken hostage and some were seen on the roof being beaten by prisoners.
The fight started as one of the gangs were kept separated began protesting on Monday night.
It was relative calm on Tuesday morning but fighting restarted when one of the prisoners were killed, reports say his body was burned.
Security officials say lethal force had to be used to control the situation after several attempts at negotiations failed.
There are concerns that the number of dead may rise.
We can’t rule out that the number of deaths might increase, eight people have suffered serious injuries in addition to the 13 who have already passed away.
There are many more with less serious injuries from the fights.
Those who lost their lives have not been identified yet， Officials are doing the counting and investigation is underway.
Outside the prison gates, anxious relatives demanded information and struggled to comprehend what was happening.
This woman says she only wants confirmation that her relative inside is dead.
This is the second unrest in this prison this year, following a series of riots in other jails.
Mexican prisons are notorious for gang activity criminal,networks running drugs, kidnapping,extortion and human smuggling,
bringing their rivalries to prisons, many of which are overcrowded.
Reforms in the criminal justice system before next year’s elections have been proposed, but for deep-rooted corruption and political intervention, there seems to be no easy or quick fix.