The leader of Los Zetas cartel in Mexico 's Veracruz is reportedly in gunbattle . Braulio Arellano Dominguez is in firefight with authorities , attorney general says . More than 12,000 people have been killed since President Felipe Calderon declared war on the drug cartels after taking office in December 2006 . Los Zetas is one of Mexico 's most advanced and violent drug cartels .
The leader of Los Zetas cartel in Mexico 's Veracruz is reportedly in gunbattle . Braulio Arellano Dominguez is in firefight with authorities , attorney general says . Los Zetas is one of Mexico 's most advanced and violent drug cartels .