Gunmen suspected of being part of Los Zetas drug cartel fired an RPG at the headquarters of a special police unit in the border city of Piedras Negras Coahuila; the rocket-propelled grenade did not explode. Piedras Negras is the sister city of Eagle Pass, Texas, and sits immediately across the border.

The attack took place on Friday evening when a group of gunmen riding in a black Yukon fired a Russian RPG-7 at the headquarters of a state police agency similar to a SWAT team, Coahuila law enforcement officials confirmed to Breitbart Texas.

The unexploded RPG ended up landing in nearby and members of the Mexican military specializing in explosives retrieved it and deactivated it.

Known as the GATES for the Spanish translation of the acronym for Special Weapons And Tactics, the police force has made a name for themselves in recent years for their frontal attack against the vicious Los Zetas cartel.

Since their creation, the secretive team of highly trained law enforcement officers has been successfully battling back the areas of control that Los Zetas exerted in the region. The police force had managed to restore a sense of peace to the area, however, in recent months Los Zetas have tried on occasion to attack Los GATES.

The drug cartel known as Los Zetas began as group of highly trained, ruthless enforcers from the Gulf Cartel that in 2010 broke away from their masters. Since their creation, Los Zetas rapidly became known as the most ruthless sadistic criminal groups through their execution methods which at times were filmed and posted on the internet. After the split, Los Zetas managed to become one of the largest drug cartels in Mexico with a presence in large parts of Mexico and with a full operational control of the U.S.-Mexico border that spanned from just shy of El Paso to just west of Laredo.

Surprisingly enough, the areas used by Los Zetas for drug and human smuggling are some of the areas with the least amount of border enforcement. Breitbart Texas has traveled to those areas where the presence of Border Patrol agents or State Troopers is minimal at best.

Ildefonso Ortiz is an award winning journalist with Breitbart Texas you can follow him on Twitter and on Facebook.