Twenty-five people were killed in a shoot-out between security forces and suspected drug criminals in northern Mexico on Thursday, a military spokesman said, dpa reported.
The fighting occurred near Ciudad Mier in Nuevo Leon state after security personnel discovered a training camp apparently used by criminals.
Three hostages were freed in the shootout, the military spokesman said.
Further details of the incident were not immediately available.
In August, the army uncovered a camp where 50 cartel members were undergoing training in Monterrey, the state capital.
Conflict between drug cartels, and with the authorities, has led to 28,000 deaths since December 2006.
President Felipe Calderon began a crackdown on organised crime from late 2006 and deployed thousands of soldiers to take part in it.