Mexican troops discovered a 122 yard long tunnel apparently aimed at crossing the U.S. border underground.

Army Gen. Alberto Duarte Mujica says soldiers found the half-built tunnel under a three-story building in the border city of Tijuana.

The army said Sunday that soldiers raided a warehouse where equipment used to build the tunnel was stored, and found 275 pounds of marijuana. They also detained seven men and two women in the Saturday raid.

The wood-lined, 6-foot high tunnel was apparently meant to extend another 144 yards to reach U.S. territory. It was equipped with electrical lights and a ventilation system.

Drug and immigrant smugglers often use such tunnels.