The security spokesman for the northern state of Tamaulipas said five people were killed in two gunbattles yesterday. Another seven people were killed earlier in the violence that began Tuesday.
The disputes between rival factions of the Gulf cartel follow the killing of leader Julian Loisa Salinas, known as "Comandante Toro," by military personnel in late April.
In another incident involving drug traffickers, Mexican federal police announced Friday they caught four suspects who allegedly used hidden compartments on buses and trucks to smuggle narcotics to the United States.