U.S. border authorities have seized a trove of drugs hidden in a sophisticated cross-border tunnel beneath the California-Mexico border, U.S. Immigration and Customs Enforcement announced Tuesday.

The tunnel, equipped with ventilation, lighting and an underground rail system, connected warehouses in Tijuana and San Diego, extending about 2,000 feet with an average depth of 31 feet and width of 3 feet, according to the San Diego Tunnel Task Force.

A haul of drugs being smuggled from Mexico to California was seized from a cross-border tunnel equipped with ventilation, lighting and an underground rail system. (U.S. Immigration and Customs Enforcement)

In a departure from earlier discoveries that consisted of mostly marijuana, authorities seized more than two tons of a variety of drugs, including opioids, methamphetamine and cocaine. The discovery of the tunnel on March 19 netted about 1,300 pounds of cocaine, 86 pounds of methamphetamine, 17 pounds of heroin, 3,000 pounds of marijuana and more than two pounds of fentanyl.

The tunnel was built near a vaunted double-layered border wall constructed during Donald Trump’s presidency, highlighting the limitations of such barriers against drug smuggling organizations.

While border walls built under Trump go underground to deter digging, they are not deep enough in some cases to stop the most advanced secret passageways.

U.S. authorities said they alerted Mexican counterparts about their investigation for help locating the entry point in Tijuana and later executed a search warrant in San Diego's Otay Mesa industrial warehouse district.

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“The Sheriff's Department remains committed to protecting the citizens of San Diego County from the dangers associated with the importation, sales, and use of illegal drugs, as well as the violent crimes associated with them,” said San Diego Sheriff William Gore. “By working collaboratively with agencies … we work tirelessly to achieve this mission.”

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In January, authorities announced the discovery of the longest smuggling tunnel ever found on the U.S.-Mexico border, stretching more than three-quarters of a mile from a small industrial building in Tijuana into San Diego. The nearby tunnel had an extensive rail-cart system, forced air ventilation, high voltage electrical cables and panels, an elevator at the tunnel entrance, and a complex drainage system.

The Associated Press contributed to this report.