The narrow tunnel spans more than 800 yards but could be even longer because its route zigzags.

The opening on the U.S. side was discovered in a lot full of wood scraps in San Diego. Officials say the tunnel started in a home in Tijuana and had a fully functioning elevator leading into it.

The tunnel entrance on the San Diego side was just a small hole in the ground that was covered with a large dumpster.

Officials say tunnels are being used more and more to ferry drugs into the U.S. This discovery comes the same week border patrol agents found a much smaller tunnel that crossed the California-Mexico border.

This video includes images from the U.S. Attorney's Office.