Inmates brawled among each other with fists and guns at a prison in western Mexico on Friday, leaving seven prisoners dead and nine others wounded.
Jalisco state authorities described the killings at the infamous Puente Grande prison complex as a fight between inmates, rather than a riot.
"There was never a riot," said the state's prison director, Jos Antonio Prez.
There was never a dispute for control of the facility.
Officials did not explain how the inmates got the two guns used in the fight.
Prez said a group of inmates began attacking other prisoners who had not caused problems, leading the rest of the prison population to turn on the attackers.
Prosecutors said five of the attackers were arrested.
More From This Section
The killings followed a prison baseball game, but it was not clear if that was related to the dispute. Nor was it clear if allegiance to rival drug gangs could have been involved in the dispute, as is often the case in prison fights in Mexico.
Of the seven dead, three were shot to death and four were beaten to death.
Six of the nine injured were beaten and three suffered gunshot wounds.
Puente Grande was the facility from which drug lord Joaquin El Chapo Guzman staged his first prison escape in 2001.