Bales of marijuana are examined by officials in Murrieta, Calif., after busting a cross-border tunnel between Tijuana, Mexico, and San Diego. (U.S. Immigration and Customs Enforcement/Associated Press) A sophisticated cross-border tunnel equipped with a rail system, ventilation and fluorescent lighting has been shut down by U.S. and Mexican officials, the second discovery of a major underground drug passage in San Diego, Calif., this month, authorities said Friday.

The tunnel found Thursday is 670 metres long — more than seven football fields — and runs from the kitchen of a home in Tijuana, Mexico, to two warehouses in San Diego's Otay Mesa industrial district, said Mike Unzueta, head of investigations at U.S. Immigration and Customs Enforcement (ICE) in San Diego.

In Mexico, the tunnel's cinderblock-lined entry dropped 24 to 27 metres to a wood-lined floor, Unzueta said. From the U.S. side, there was a stairway leading to a room about 15 metres underground that was full of marijuana.

"It's a lot like how the ancient Egyptians buried the kings and queens," Unzueta said.

He said the tunnel discovered Thursday and another found in early November are believed to be the work of Mexico's Sinaloa cartel, headed by that country's most-wanted drug lord, Joaquin (El Chapo) Guzman.

"We think ultimately they are controlled by the same overall cartel but that the tunnels were being managed and run independently by different cells operating within the same organization," Unzueta said.

Rail tracks for cart

A U.S. agent shown in a tunnel Thursday that authorities say was used to move drugs between Tijuana, Mexico, and San Diego, Calif. (U.S. Immigration and Customs Enforcement/Associated Press)The passage found Thursday is one of the most advanced to date, with an entry shaft in Mexico lined with cinderblocks and a rail system for drugs to be carried on a small cart, Unzueta said.

Authorities seized more than 18,000 kilograms of marijuana. Three men were arrested in the United States, and the Mexican military raided a ranch in Mexico and made five arrests in connection with the tunnel, authorities said.

U.S. authorities have discovered more than 125 clandestine tunnels along the Mexican border since the early 1990s, though many were crude and incomplete.

U.S. authorities do not know how long the latest tunnel was operating. Unzueta said investigators began to look into it in June on a tip that emerged from a large bust of marijuana, cocaine and methamphetamine by the San Bernardino County Sheriff's Department.

U.S. authorities followed a trailer from one of the warehouses to a Border Patrol checkpoint in Temecula, Calif., where they seized 12,520 kilograms of marijuana.

The driver was arrested, along with two others who went to a home in suburban El Cajon that had $13,500 US cash inside.

"That [trailer] was literally filled top to bottom, front to back," Unzueta said. "There wasn't any room for anything else in that tractor-trailer but air."

About 2,700 kilograms of marijuana were found in a "subterranean room" and elsewhere in the tunnel on the U.S. side, authorities said. Mexican officials seized about 3,600 kilograms of pot at a ranch in northern Mexico, bringing the total haul to more than 18,000 kilograms.

The discovery of the cross-border tunnel earlier this month marked one of the largest marijuana seizures in the United States, with agents confiscating the marijuana they said was smuggled through the underground passage. One of the warehouses involved in the tunnel discovered Thursday is only a half-block away.

Several sophisticated tunnels have ended in San Diego warehouses. ICE began meeting with landowners last month to warn them about leasing space to tunnel builders.

"These owners of warehouses, they need to know their customers, they need to know who's in there leasing these things," Unzueta said.