Twenty-nine people died Thursday in fights between rival drug gangs that spread across the towns of Tubutama and Caborca in northern Mexico.

All the dead were members of armed drug gangs and none of them have been identified, Jose Larrinaga Talamantes, an official from the state attorney's office, told reporters.

Nine others were arrested by police and six of whom had serious, but non life-threatening injuries. Seven pieces of weapons and eight trucks were seized on the battle scenes, Larringa added.

Mexican army closed Tubutama following reports of shootings.

On Wednesday, police in Nuevo Leon, also on Mexico's northern border, found 12 bodies in four improvised graves used by drug traffickers.

Mexican media estimate that at least 2,500 people have been killed so far this year during clashes between drug gangs vying for lucrative routes into Mexico's northern neighbor, the United States.