Two tons of cocaine and seven tons of marijuana, worth nearly $22 million, were seized by federal agents who believe this to be the "longest cross-border tunnel ever discovered."
The 800-yard tunnel route begins at a house in Tijuana, Mexico, and ends in the Otay Mesa neighborhood of San Diego.
The tunnel was furnished with ventilation systems, lights and even a large elevator that led into a closet inside the Tijuana residence, officials said.
"On the surface, few would ever suspect that traffickers were moving multiton quantities of cocaine and marijuana worth tens of millions of dollars in such an unassuming way, through this rabbit hole in the ground, in full view of the world around it," said U.S. Attorney Laura Duffy in the release.
The six people were arrested in San Diego and charged with various drug trafficking charges, police said.
"This case is a strong reminder of the vulnerabilities that exist along the Southwest border," said Hunter Davis, director of air operations for Customs and Border Protection, Air and Marine Operations.
Since 2006, 13th large-scale operational drug smuggling tunnels have been discovered along the California border, federal agents said.