Altamira prison brawl

On 15 October 2011, in the border city of Matamoros, Tamaulipas, 20 inmates were killed and 12 were severely wounded in a prison brawl.[10] Some sources revealed that the killings were "planned executions."[11] Earlier on 6 August 2010, 14 inmates were also killed in a riot at the federal prison in Matamoros.[12] Moreover, in 1991, the time when Juan García Ábrego was the supreme leader of the Gulf Cartel, the federal prison in Matamoros experienced the massacre of 18 people.[13][14][15] In the nearby border city of Reynosa, Tamaulipas, 21 inmates were killed after a shooting inside the prison on 20 October 2008.[16]

On 26 July 2011 in Ciudad Juárez, Chihuahua, a prison brawl left 17 inmates dead and 4 injured after "one group of inmates attacked rivals from another drug gang."[17] Some of the corpses were shot with assault rifles, and authorities investigates whether the weapons used in the attack were "stolen from prison guards, homemade or smuggled" inside the prison.[18] Surveillance videos show how two gangs of the Sinaloa Cartel and the Juárez Cartel stormed the prison with assault rifles.[19]

On 19 February 2012, in the city of Apodaca, Nuevo León, 44 were killed and 12 were injured in a prison riot; the brawl was, according to local authorities, between the Gulf Cartel and Los Zetas, their former allies.[20] In the state of Durango, 19 inmates were killed in the prison of Gómez Palacio on 25 August 2009;[21] in the same prison on 21 January 2010, about 23 inmates were killed in a brawl.[22] On 19 May 2011, a shooting inside a prison in Durango left 8 prisoners dead,[23] and on 15 November 2010 a group of gunmen threw a grenade inside the prison.[24] In Tijuana, Baja California on 18 September 2008, nearly 19 inmates were killed in a brawl between rival drug cartel members.[25]

In Mazatlán, Sinaloa on 14 June 2010, a group of gunmen entered a prison, killed the guard, then entered a cell and massacred 29 people.[26]