The workers, aged between 35 and 25, and the boy were killed by shotgun blasts Saturday afternoon in violence that appeared to be perpetrated by drug cartels, Baja California officials told The San Diego Union-Tribune.

A total of seven people died Saturday in Tijuana violence, the newspaper said. One incident, however, provided leads for police on who is ordering the slayings, which have claimed 715 lives in the city since Jan. 1.

Authorities said three gunmen fleeing the scene of an attack on a police officer were chased and intercepted by authorities, and one of them, identified as Roberto Castaneda, 42, is a state police investigator. Police told the Union-Tribune that Castaneda confessed to being part of a cell run by Filiberto Parra Ramos, nicknamed "La Perra," who in turn allegedly works for the cartel of Teodoreo Garcia Simental, known as "El Teo."

Authorities told the newspaper that Garcia Simental is one of the drug lords fighting for control of the lucrative Tijuana drug trade.