Reporting from Mexico City - Drug traffickers fighting to control northern Mexico have turned their guns and grenades on the Mexican army, authorities said, in an apparent escalation of warfare that played out across multiple cities in two border states.

In coordinated attacks, gunmen in armored cars and equipped with grenade launchers fought army troops this week and attempted to trap some of them in two military bases by cutting off access and blocking highways, a new tactic by Mexico's organized criminals.

latimes.com