At least 13 people have been killed in three separate gun battles in the Mexican border city of Matamoros, in what could be the first sign of a predicted upsurge in violence following the July capture of the Zetas leader Miguel Angel Treviño, alias “Z40.”

In the first of three clashes, which all took place on November 3, two armed groups thought to be from rival criminal organizations, opened fire on each other on the main highway from Matamoros to the city of Reynosa along the US border, reported the BBC. Four men and a woman were killed.

Hours later, Mexican Marines chased and shot at an armed group traveling in various vehicles on the same highway, reported authorities in Tamaulipas state, killing four. Another four men were killed after they attacked Marines in the center of Matamoros.

Following each confrontation, authorities seized weapons, ammunition, tactical equipment and vehicles. 

The violence began when an armed group identified as “Los Ciclones” were chased by assassins from the Gulf Cartel, after refusing to hand over arms and cede the Matamoros trafficking corridor, or “plaza” as it is known in Mexican underworld parlance, reported Vanguardia and El Informador.

InSight Crime Analysis

Following the capture of the Zetas leader Treviño, alias Z40, last July, various analysts, including InSight Crime, warned a resulting upsurge in violence was a strong possibility. Taking out Treviño left territory and power up for grabs, for which both rival organizations like the Gulf Cartel and warring elements within the Zetas’ fractured structure were expected to fight.

SEE ALSO: Coverage of the Zetas

Sunday’s violence is the first indicator of these predictions becoming a reality, especially if reports that a fight for control of the Matamoros plaza sparked the clashes are correct. Still, Tamaulipas is a notoriously difficult place to obtain accurate accounts of the fighting, and the presence of the Ciclones indicates that it may have been more of an internal fight amongst Gulf Cartel factions than anything related to the Zetas. To be sure, Matamoros is the birthplace of the Gulf Cartel.

In either case, the Matamoros battles could be a harbinger of things to come in Tamaulipas, one of Mexico’s most violent states. The Zetas, which began as armed wing of the Gulf Cartel, split from the organization in 2010. The two have been fighting a fierce territorial battle ever since.