At least 13 people are reported dead across the Brownsville border. This following three separate clashes between Mexican marines and gunmen in Matamoros, Tamaulipas. Officials in northern Mexico say, the gun battles happened Sunday afternoon when gunmen attacked troops in different parts of Matamoros.

The area has been known to be a battleground by the rival Gulf and Zetas drug cartels. Mexican officials describe the attackers only as “armed civilians.”