Authorities say they've discovered the longest smuggling tunnel ever found underneath the US-Mexico border.
The more than three-quarter mile long shaft ran from an industrial area in Tijuana, Mexico to the San Diego area, according to a Wednesday press release from U.S. Customs and Border Protection.
Mexican law enforcement discovered the entrance late last August. It was extensively mapped as part of a multi-year, inter-agency, high-tech investigation to uncover such tunnels.
Officials say the approximately 5-and-a-half-foot-tall by 2-foot-wide tunnel had an average depth of 70-feet below the surface and was equipped with a rail system, high voltage electrical system, elevator, and drainage and ventilation system.
The 4,309 foot long tunnel bests the previously known longest tunnel found in 2014, also in the San Diego area, by 1,343 feet.