Four people were killed in a shootout between suspected gunmen and soldiers in Saltillo, the capital of the northern Mexican state of Coahuila, the federal Attorney General's Office said.

State police received a report about a shootout Tuesday at an intersection between "military personnel and a group of armed civilians," the AG's office said.

Officers who arrived on the scene found the bullet-riddled bodies of four men inside an SUV that had been hit by gunfire, the AG's office said.

Four assault rifles and 548 rounds of ammunition were also discovered inside the vehicle.

Coahuila, which is on the border with the United States, has been the scene in recent months of clashes between members of rival drug cartels.

A nephew of Coahuila's acting governor was gunned down on Nov. 11 in Saltillo by suspected drug traffickers, while the army engaged gunmen in shootouts over a period of three days in the capital that left one person dead.

A total of 15,270 people died in drug-related violence in Mexico last year, and more than 40,000 people have died since President Felipe Calderon declared war on the country's cartels shortly after taking office in December 2006.

Calderon has deployed tens of thousands of soldiers and Federal Police officers across the country to combat drug cartels and other criminal organizations.

The anti-drug operation, however, has failed to put a dent in the violence due, according to experts, to drug cartels' ability to buy off the police and even high-ranking officials.