Tucson Sector Border Patrol agents and Mexican law enforcement discover an incomplete cross-border tunnel during a routine bi-national sweep on December 17. 

Tucson Sector Border Patrol agents and Mexican law enforcement found an incomplete cross-border tunnel running below both cities of Nogales.

The entry point was submerged under an international waterway channel below both cities. The tunnel ran adjacent the Port of Nogales, DeConcini Crossing and ended under a parking lot in Nogales, Arizona. 

The 50-foot-long tunnel had about 44 feet in the United States. It was 2-by-2 feet in diameter.  Agents found digging tools, which they say indicates the tunnel was still in the process of being built.

Agents will monitor the tunnel until it's filled with concrete. Anyone with information can leave anonymous tips at 877-872-7435.