A major drug smuggling tunnel about the length of a six football fields has been found by US authorities running from Mexico to a warehouse in an industrial area in San Diego.
The secret passage from Tijuana to San Diego featured rail and ventilation systems, electricity and reinforced walls, authorities said.
It measures 1,744 feet in length and is 61 feet deep, agents with Homeland Security Investigations said on Monday.
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 tunnel running between Tijuana, Mexico and the US is estimated to be about 1,744 feet long, 61 feet deep and 4-feet in diameter, with reinforced walls, a rail system, electricity and a ventilation system
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
A photograph shows the inside of a cross-border tunnel between Mexico and the U.S. after the announcement of the discovery of subterranean tunnel inside a warehouse in San Diego
A law enforcement officer stands by the opening of a cross-border tunnel on Monday
A Mexican Armed Forces soldier stands outside a house where the opening of a cross-border tunnel between Mexico and the U.S. was discovered, in Tijuana, Mexico,
Agents were conducting surveillance on a 'known drug stash house' in National City, south of Downtown San Diego.
U.S. 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 and have pleaded not guilty.
The tunnel is in one of the most fortified stretches of the border, illustrating the limitations of border walls.
The tunnel ran the length of six football fields on U.S. soil to a warehouse in an industrial area but its entry point was here
About 1,700 pounds of cocaine, 164 pounds of meth and 3.5 pounds of heroin were seized from the warehouse, where an exit point was carved out of the floor
It was built in one of the most fortified stretches of the border, illustrating the limitations of former President Donald Trump's border wall
While considered effective against small, crudely built tunnels called 'gopher holes,' walls are no match for more sophisticated passages that run deeper underground.
The latest passage which was discovered on Friday, ran one-third of a mile to Tijuana. It was 4 feet in diameter and about six stories deep.
The type of drugs seized may signal a shift from the multi-ton loads of marijuana that were often found in discoveries before California legalized pot for recreational use in 2019.
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 an advantage of being able to carry huge loads at lightning speed.
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.
A photograph shows drugs seized after the discovery of a cross-border tunnel
The tunnel was connected to warehouse 300 feet north of the U.S.-Mexico border
On Monday, armed guards watched over a small shaft with a ladder that descended into the tunnel.
After staking out a home that was recently used to stash drugs, officials began making traffic stops of vehicles that had been there or at a warehouse near the border, turning up boxes full of cocaine, according to a federal criminal complaint filed in San Diego.
They followed two suspects who left the house in a vehicle and drove to the warehouse.
'Upon searching the warehouse, agents uncovered a sophisticated border tunnel exit point carved out on cement floor,' said U.S. Attorney Randy Grossman.
'We allege our defendants were driving into garage and loading and dropping off cardboard boxes full of drugs to further the movement and distribution of drugs into the United States.'
They raided the properties - finding no other drugs at the warehouse, but a tunnel opening carved into the cement floor, federal prosecutors said.
The tunnel is the 91st in the Tijuana-San Diego area and the 272nd tunnel found along the entire border since 1993.
Authorities have found about 15 sophisticated tunnels on California's border with Mexico since 2006. The largest was a huge 4,309-foot tunnel in Tijuana that was discovered by federal agents in January 2020.
The sophisticated tunnel was equipped with air ventilation, electricity, a rail cart system and an elevator.
Many tunnels, including the one announced Monday, are in San Diego's Otay Mesa industrial area, where clay-like soil is conducive to digging and warehouses provide cover.
The cross-border passages date back to the early 1990s and have been used primarily to smuggle multi-ton loads of marijuana.
The U.S. Drug Enforcement Administration said in 2020 that they are generally found in California and Arizona and associated with Mexico's Sinaloa cartel.
Authorities declined to link the latest tunnel to any specific cartel. They claimed victory despite not knowing how long it had been operating.
'There is no more light at the end of this narco-tunnel,' said Randy Grossman, U.S. 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, U.S. authorities must fill the U.S. side of tunnels with concrete after they are discovered.