Four American men arrived in the border town of Matamoros on Friday, Mexico, in a white van with North Carolina license plates. But after he crossed the border, attackers came to attack his vehicle and kidnapped the travelers.

According to Andres Manuel Lopez ObradorThe President of Mexico, the victims are US citizens who “crossed the border to buy medicine in Mexico and there was a confrontation between groups and they were arrested”.

Shortly after they entered Mexico, unknown gunmen fired on the vehicle’s passengers. The four Americans were put in a car and taken away by armed men, the police said.

During the kidnapping a Mexican has diedUS Ambassador to Mexico Ken Salazar said in a statement Monday.

López Obrador assured that the FBI is working with the Mexican Secretary of Security and maintains “communications” with the head of that office, Rosa Icela Rodríguez.

Meanwhile, the The US State Department warned its citizens not to travel to the violent state of Tamaulipasas a result of kidnappings and other crimes.

According to that warning, organized crime activity there includes shootings, murders, robberies, kidnappings, enforced disappearances, extortion and assaults.