A truck that left the U.S. Logistics Center in Brownsville, Texas, was hijacked by armed men near the U.S.-Mexico border earlier this month.

The armed robbery took place in the Mexican city of Matamoros, just south of Texas on June 7th. It was carrying 11,500 non-immigrant visas, which were to be given to Mexican citizens who had legally applied, and been approved, for visas to travel across the border and within the United States.

There has been little information released about the armed men who hijacked the vehicle. The area where the incident took place has been historically controlled by the Gulf Cartel, a dangerous Mexican crime syndicate.

Border patrol agents have been given a list of the visa identification numbers, in order to prevent illegal border crossings using the stolen cards.

News agencies, such as Breitbart.com, note that there is little in the way to stop the cards from being transported back into the U.S., to be used as identification for people that have already made it into the country.