U.S. Customs and Border Protection (CBP) officers discovered an abandoned tunnel on a tip.

Tucson Sector Border Patrol agents located a collapsed tunnel after receiving a report about a suspicious opening near the Raul Hector Castro Port of Entry, according to a statement from CBP Arizona.

Although the tunnel collapsed roughly 25 feet from its opening, agents confirmed that it extended into the United States by 60 yards. It was located near a sewer line and apparently cut through a tunnel that was previously dug in the same location.

Transnational criminal organizations (TCOs) use tunnels like the one found in Arizona to smuggle humans and narcotics into the United States.