The Mexican army says, it has killed 27 suspected drug cartel gunmen in a clash near the US border. The army said a patrol came under fire as it approached an apparent training camp that had been spotted during an aerial search. Two soldiers were wounded in the fighting in Tamaulipas state. Tamaulipas has been a major focus of violence between drug cartels competing for control of smuggling routes into the US. The rival Zetas and Gulf cartels have been waging a bloody turf war there. More than 28,000 people have died in drug-related violence in Mexico since President Felipe Calderon ordered the army and federal police to fight the cartels in 2006.