At least 11 people were killed in a series of gunbattles in the northern Mexico border state of Tamauilpas, authorities said.
Officials said the shootouts in the border city of Reynosa and the nearby town of Rio Bravo started late Sunday, reports AP.
Gunmen hijacked vehicles and used them to block streets, and spread bent nails to puncture tires to facilitate their getaways.
Authorities called in a helicopter to support ground patrols moving to break up the roadblocks.
One group of four gunmen was killed near a gas station after they opened fire on a military patrol, officials said.
Three other bodies were discovered at other points around Rio Bravo.
Police found 13 improvised armoured vehicles, which are usually light trucks with welded steel plating.
Such vehicles are often used by drug gangs in Tamaulipas. Officers also found six hand grenades, 17 40-mm rifle-launched grenades and about three dozen guns, including a .50-caliber sniper rifle.