U.S. Border Patrol agents discovered the tunnel under construction Friday.
They say the tunnel entrance is located within the Grand Avenue Drainage System in Mexico and continues north into the United States below a parking lot.
The hand-dug tunnel extends about 19 feet north, 15 feet of which is located within the U.S.
Authorities say the tunnel is about 2 feet wide and 3 feet tall. It contained a breaker bar, safety glasses, knee pads, crow bar, sledge hammers, chisels and hoes.