The secret passage from Tijuana to San Diego featured rail and ventilation systems, electricity and reinforced walls, authorities said. It was discovered near San Diego's Otay Mesa border crossing in an area where more than a dozen other sophisticated tunnels have been found in the last two decades.

The latest passage, discovered Friday, ran one-third of a mile (532 m) to Tijuana. It was 4 feet (1.2 m) in diameter and about six stories deep.

The tunnel exited the United States in a nondescript warehouse named "Amistad Park" on a street that is busy with large semitrailers during the day but quiet at night. On Monday, armed guards watched over a small shaft with a ladder that descended into the tunnel.

US authorities said it was unknown how long the tunnel had been operating and what amount of drugs, if any, got through undetected. They seized 1,762 pounds (799 kg) of cocaine, 165 pounds (75 kg) of meth, and 3.5 pounds (1.6 kg) of heroin in connection with the investigation.

Six people, ages 31 to 55, were charged with conspiring to distribute cocaine. All are Southern California residents.

Hard drugs, such as heroin, methamphetamine, and fentanyl, are typically smuggled through official border crossings from Mexico because their small size and lack of odor make them difficult to detect. But tunnels give smugglers the advantage of being able to carry huge loads at lightning speed.

"There is no more light at the end of this narco-tunnel," said Randy Grossman, US attorney for the Southern District of California. "We will take down every subterranean smuggling route we find to keep illicit drugs from reaching our streets and destroying our families and communities."

By federal law, US authorities must fill the US side of tunnels with concrete after they are discovered.

NEXT WEEK: Watch the LIVE CBN NewsChannel Airing of 'Biden's Border' - 8:00 pm Eastern Monday (5/23) and 10:00 pm Eastern Wednesday (5/25).

In addition, such tunnels also give the cartels a way to secretly smuggle paying customers illegally into the US.

Biden's Border, a 60-minute CBN News special shows how a skyrocketing number of migrants are coming from all over Central America and beyond. These individuals are crossing the US-Mexico border and are then promptly released without US court dates in a beleaguered system that's growing more overwhelmed by the day. (Screengrab image)

"Due to the lenient immigration policies now in place, most will never face a judge. Usually, you're given a court date, and you're supposed to appear, which most don't appear," Republican congressional candidate Mayra Flores said. "But at least you're given a court date. Now, they're not even given a court date."

Biden's Border offers a shocking lens into the overarching issue, law enforcement's dire predictions, and the troubling ways landowners and citizens alike are being impacted.

"Little by little, our original Constitution is being ripped apart," a Texan named Dottie warns in the documentary. "What they go through to protect us and our properties. Without our border patrol, we don't have a country." Subscribe for free to Breaking Christian News here

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