Mexican authorities arrested 12 people, including a minor, for cartel-related violence in Matamoros.

Mexican police are out in force in the city to try and maintain control.

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"We must recognize that we have a problem. We also recognize that we have to work and seek the best solutions for it, that the circumstances we are in, increase the security that we are offering to the population. We would like to say and guarantee 100 percent but well, we'd be lying," Tamaulipas Governor Américo Villarreal Anaya said.

Mexican authorities say the shootouts and street blockades are a result of rival drug cartels, and at least one person has been killed.