A family traveling home from a vacation in Mexico was attacked Saturday night by armed gunmen just south of Texas.

The attack, which occurred in the state of Tamaulipas, killed the family’s 13-year-old son and left three others injured. The identities of the family members have not yet been officially disclosed, but the state attorney general confirmed that the boy was a U.S. citizen and that his parents are permanent residents.

The family was reportedly returning from visiting relatives in San Luis Potosi. While their home in the U.S. has not been confirmed by authorities, they were traveling in a Chevrolet SUV with Oklahoma license plates.

The stretch of highway the family was attacked on is considered “high risk” for such attacks. The motive and identities of the family’s assailants have not been disclosed but the attack comes on the heels of recent attacks on travelers by cartels near the U.S.-Mexico border.

In November, nine women and children were killed in a cartel ambush while traveling just south of the Mexican border to visit relatives. The family lived in an offshoot Mormon community in northern Mexico and had reportedly had run-ins with local cartels in the past.

Since then, the U.S. State Department has issued a heightened warning for travelers in Mexico, urging caution in all parts of the country. Particular focus has been put on Tamaulipas, which the Department urges travelers to avoid entirely

Community police patrol in the Mexican indigenous town of Cheran, which is practically an independent state won back by locals from illegal loggers and drug cartels Community police patrol in the Mexican indigenous town of Cheran, which is practically an independent state won back by locals from illegal loggers and drug cartels Photo: AFP / Pedro PARDO