Nogales, Arizona - U.S. Border Patrol agents and Mexican Federal Police discovered an incomplete cross-border tunnel running underneath the streets of Nogales on Wednesday.

U.S. Border Patrol agents and Mexican Federal Police discovered an incomplete cross-border tunnel running underneath the streets of Nogales on Wednesday.

The tunnel was found during a routine, bi-national tunnel sweep of the stormwater drainage system that serves both sides of the border.

The tunnel's entrance was concealed in the floor of an existing drainage system with a pile of dirt and capped with a Styrofoam and concrete mixture. At its entrance, the tunnel was approximately three feet wide and over four feet tall. It was located 10 feet underground and extended 20 feet into the United States.

U.S. Border Patrol and Mexican authorities will continue to monitor and inspect the incomplete tunnel until it is properly secured and remediated with concrete filler. This is the 124th tunnel discovered in the Tucson Sector since 1990.

U.S. Border Patrol frequently works with strategic partners to conduct joint operations, and binational cooperation with Mexico plays a vital role in border security. During the week of Thanksgiving, U.S. Border Patrol partnered with the Mexican Federal Police Force on a four-day operation to target narcotics and human smugglers near Nogales, Sonora. These efforts aim to prevent the movement of illegal contraband or persons across the border.