Mexican soldiers killed at least 12 suspected criminals in a running gun battle across the central state of Zacatecas.
The clash erupted on Wednesday when the two sides ran into each other in the city of Rio Grande, sparking a pursuit along 50 kilometers (31 miles) that ended in the town of Sombrerete, a state official told AFP on condition of anonymity.
The official said the death toll may be higher. Defense Ministry officials were not immediately available for comment.
Zacatecas has not been spared from the drug violence afflicting Mexico that has left at least 70,000 people dead across the country since 2006, when troops were deployed to battle cartels.
Earlier, the navy said marines had detained 18 people, including 12 minors and a woman holding a baby, on New Year's Eve in the Zacatecas town of La Estacion San Jose.
The marines seized a cache of weapons, including two grenade launchers, and bags of cocaine and marijuana from the group.