The small Mexican town of Villa Union was rocked Saturday by an hour-long shootout between authorities and gunmen who were believed to be drug cartel-affiliated. The armed aggressors stormed the town in trucks and targeted government offices, forcing the hand of state and federal authorities.

At least 21 were killed in the gunfight.

Coahuila Gov. Miguel Angel Riquelme confirmed that four of the dead were police and the remaining 10 were from the armed aggressors, believed to be members of the Cartel of the Northeast. Several local government employees are also missing following the conflict. Seven more gunmen were later confirmed to have been killed, bringing the death toll to 21.

Video footage taken from the scene shows a pickup truck with “C.D.N.” written on the side, pointing to the involvement of the “Cartel del Noreste,” which translates to Cartel of the Northeast.

“These groups won’t be allowed to enter state territory,” Gov. Requilme said.

Police and security forces will stay in Villa Union until peace has been restored and the town is deemed safe from further attacks. Villa Union is a town of 3,000 located in the state of Coahuila near the U.S. border, roughly one hour from Eagle Pass, Texas.

This attack on a town near the U.S. border comes only weeks after several U.S.-Mexico dual citizens and their children were killed by gunmen while traveling between the states of Sonora and Chihuahua.

President Donald Trump has recently announced his intention to have cartels designated as terrorist groups.