Mexican troops killed 19 suspected Sinaloa cartel members in a firefight near Culiacan after being attacked by over 30 people, according to the defense ministry.

The violence follows the July arrest of cartel co-founder Ismael “El Mayo” Zambada, which triggered infighting between his faction and the sons of Joaquin “El Chapo” Guzman.

Zambada’s arrest intensified tensions within the cartel, and the suspects killed were believed to be linked to his faction, CBS News has reported.

El Chapo’s sons, involved in a brutal fentanyl-trafficking operation, are facing charges in the U.S., while El Chapo is serving a life sentence.

Written by B.C. Begley