A deadly riot broke out during family visiting hours Thursday at a prison in the violence-plagued state of Sinaloa in northwestern Mexico.

Axar.az reports, citing ABC News, that the violence occurred Thursday morning at the El Castillo Penitentiary in the port city of Mazatlan.

Sinaloa’s Public Security Secretariat said on X that nine inmates and one family member were killed in the incident, while 16 prisoners were taken for medical treatment after being injured. Local media reported that inmates used firearms during the fight.

Authorities have not yet said how the deaths occurred.

Following the clash, members of the army, National Guard, navy and state security forces entered the prison to restore order. Mexico's federal security cabinet said the prison, which houses 1,800 inmates, is now “under control.”