Prison fight and second clash leave 12 dead in Mazatlán, Mexico, over two days

Thursday riot at El Castillo prison

On Thursday morning, a fight broke out inside El Castillo penitentiary in the port city of Mazatlán, in the Mexican state of Sinaloa. Sinaloa's public security secretariat said on X that nine inmates and one family member were killed, while 16 prisoners were taken for medical treatment after being injured. NZZ reported that the shots were fired during visiting hours, and local media said inmates used firearms during the fight, although authorities had not yet said how the deaths occurred. Sources differ on the tenth victim: Europa Press and France 24 describe a minor visiting a relative, while Mediafax and the Irish Examiner describe a family member.

Security forces and the official toll

After the clash, soldiers, National Guard members, navy personnel 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". France 24 reported that dozens of soldiers and police entered with long guns and riot shields, while an armored vehicle and ambulances arrived and relatives gathered outside asking for information. Sinaloa's public security secretary Sinuhé Téllez posted a video on social media giving the official count, and he offered no further detail about what led to the fight.

Nine people deprived of liberty and a minor who was visiting lost their lives, and 16 people deprived of liberty were injured.

The injured were transported to a hospital, according to the same account.

Second fight on Friday

On Friday, a second fight inside a module of the prison killed two more people, according to a statement from the Sinaloa security secretariat reported by Europa Press. The statement said two persons deprived of liberty died in a riña and that the rest of the prison population was well, with authorities maintaining a presence inside and outside the centre. ANSA, citing Milenio, said the new deaths brought the toll to 12 over two days. The identities of the two dead were not released, and the state prosecutor's office was informed and opened an investigation into the causes. Prison social workers were contacting the victims' families to provide information about the circumstances.

Government response and prison conditions

Claudia Sheinbaum said at a press conference on Friday that her government is working with Sinaloa governor Graciela Domínguez to reinforce the state's prison system. Mexico has 276 prisons, including 14 federal penitentiaries and 249 state prisons, and the prison population reached 261,388 people as of February according to official figures. Analysts cited by Mediafax and the Irish Examiner link overcrowding, driven partly by pre-trial detention that keeps thousands of prisoners without a sentence, and insufficient staff to corruption and violence inside prisons. The Irish Examiner also reports that the Thursday riot comes as Mexico's government faces pressure from the Trump administration to crack down on cartels.

Cartel violence in Sinaloa

Violence erupted in Sinaloa in September 2024 amid an internal power struggle between two factions of the Sinaloa Cartel. One faction is led by the sons of convicted former drug lord Joaquín "El Chapo" Guzmán, known as Los Chapitos, and the other follows Ismael "El Mayo" Zambada, another detained former cartel leader. AFP reports that the internal war has left more than 1,000 dead since 2024, and that several members of the Sinaloa cartel are held in the state's prisons. France 24 notes that the Thursday riot is the second such incident in a Sinaloa prison in 2026. Seven inmates died in a prison revolt in Culiacán, the state capital, at the end of May.