A new brawl at the El Castillo prison in Mazatlán, Mexico, left two inmates dead on Friday 9 October. This follows Thursday’s riot, which killed 10 people at the same prison and was covered in our first report.
Mazatlán is a popular Pacific resort for US tourists, and Sinaloa’s security situation is closely followed in the United States. Reforma and El Financiero report the new fight but give no cause.
President Claudia Sheinbaum said on Friday that security in Sinaloa’s prisons will be reinforced. The reports we reviewed name no victims and report no arrests.
Key Facts
—Who. Two inmates died in the new brawl; names have not been released.
—What. A new riña (a brawl between inmates) at the El Castillo prison, a day after a riot that left 10 dead.
—Where. Centro Penitenciario El Castillo, Mazatlán, Sinaloa state, Mexico.
—When. Friday 9 October 2026, after the riot of Thursday 8 October 2026.
—Official line. President Sheinbaum says security in Sinaloa’s prisons will be reinforced; family visits are suspended.
—Status. As of 9 October 2026, 18:15 GMT
What We Know
Reforma and El Financiero report a new riña at the El Castillo prison on Friday 9 October. A riña is the Spanish word for a brawl between inmates.
The new fight left two inmates dead. The reports we reviewed give no names, no cause and no time.
No arrests have been reported in connection with the Friday fight. Officials have not said whether it is linked to Thursday’s riot.
On Thursday 8 October, gunfire and a brawl between inmates broke out at El Castillo during visiting hours. The Sinaloa Public Security Secretariat, relayed by Proceso and Noroeste, put the toll at 10 dead and 16 injured.
The dead were nine inmates and one visitor, a young child. El Financiero puts the start at around 10:00 local time, during visiting hours.
Sinaloa security secretary Sinuhé Téllez López is reported by Mexican outlets to have called it a confrontation between inmates. He is also reported to have ruled out that an armed group entered the prison.
El Financiero and N+ report that the attack aimed at Eduardo Jonathan Martínez Larios, known as “El Owen”. They describe him as linked to the Chapitos faction of the Sinaloa Cartel and part of the Martínez Larios family network in southern Sinaloa.
Those reports say he was among the dead. This is the outlets’ reporting, and officials have not confirmed a motive.
His brother, Gabriel Nicolás Martínez Larios, known as “El Gabito”, was arrested in Mazatlán on 1 June 2026, according to Mexican press. He was handed to federal authorities.
El Financiero reports that El Castillo holds 2,217 inmates. Its official capacity is 1,800.
Family visits at El Castillo were suspended after Thursday’s riot, according to the state security secretariat. The Sinaloa State Attorney General’s Office, the Fiscalía General del Estado, is investigating that riot.
Violence at the prison is not new. On 24 September 2026 two inmates died after a fight in the workshop area, according to the state security secretariat.
Sheinbaum said on Friday 9 October that security in Sinaloa’s prisons will be reinforced. El Financiero’s headline says she will “bring the prisons in line” (“meterá en cintura”) and that vigilance will be reinforced.
She said the federal government is in contact with interim governor Graciela Domínguez Nava. She added that the Security Cabinet is supporting.
Domínguez Nava has been interim governor since 25 August 2026. She took over after Rubén Rocha Moya took indefinite leave.
What Is Not Known
Officials have not said what caused Friday’s fight. The reports we reviewed also give no time for it.
The identities of the two dead have not been released. It is not known whether the fight is linked to Thursday’s attack.
It is not known how weapons got into the prison. Officials have not explained it.
It is not known whether family visits will resume. Final tallies for both days could still change.
Officials have not confirmed a motive for Thursday’s attack. The reports naming a target are the outlets’ own reporting.
What It Means for Travelers and US Readers
The reports we reviewed describe fighting among inmates inside the prison. They describe the violence as taking place inside the prison.
US travellers should check the State Department’s official travel advisory for Sinaloa before booking or travelling. We do not state its level here.
Relatives of inmates face a practical effect, because family visits are suspended. It is not known when they will resume.
For US readers who follow Mexican security, two deadly incidents in two days at one prison draw attention. Federal attention has followed, since Sheinbaum has promised reinforced security.
Whether that changes conditions at El Castillo is not yet known. We have not independently verified these figures, which come from Mexican outlets.
We will correct our reports if authorities revise the tolls. Further coverage is on our Mexico page.
Frequently Asked Questions
What happened at El Castillo prison on 9 October?
Reforma and El Financiero report a new brawl between inmates that left two inmates dead. No cause, time or names were given in the reports we reviewed.
How does it relate to Thursday’s riot?
Thursday’s riot, on 8 October, left 10 dead and 16 injured, according to the Sinaloa Public Security Secretariat as relayed by Proceso and Noroeste. Officials have not said whether the two events are linked.
What has President Sheinbaum said?
On Friday 9 October she said security in Sinaloa’s prisons will be reinforced. She said the federal government is in contact with interim governor Graciela Domínguez Nava and that the Security Cabinet is supporting.
Should US travellers check advisories for Mazatlán?
US travellers should check the State Department’s official travel advisory for Sinaloa before they travel. We do not state its level here.
Sources
Sinaloa State Public Security Secretariat statements, as reported by Reforma · El Financiero (second riot) · El Financiero (Sheinbaum) · Proceso · Noroeste
This article was produced by The Rio Times’ automated newsroom system. How we use AI · Report an error · Editorial responsibility: Matthias Camenzind, Editor-in-Chief