Some of the biggest rival gangs of MS-13 include the 18th Street, Street Thug Criminals and the South Side Locos. In March 2012, the government of El Salvador mediated a truce between the MS-13 and 18th Street gang, otherwise known as "M-18" or "Barrio 18." The truce was supported by the Organization of American States and the Catholic Church.
Mara Salvatrucha 13, with the infamous moniker of MS-13, originated in Los Angeles, California. MS-13 mainly comprised adolescent Salvadorians who were terrorized and exploited by other gangs. As MS-13 grew in notoriety, its members became involved in felonious undertakings, such as burglaries, narcotic sales, illegal firearms deals, extortion, rape and murder. Although the majority of its victims are members of its rival gangs, some criminal acts of MS-13 have claimed innocent civilian lives.