During searches related to the investigation on Tuesday, Mexican authorities and agents with the multi-agency San Diego Tunnel Task Force recovered an estimated 14 tons of marijuana, ICE said.
Mexico is in the grip of brutal drug cartel violence that has claimed more than 42,000 lives since President Felipe Calderon took office five years ago and sent the military to crush the powerful gangs.
Mexican cartels have excavated scores of tunnels under the U.S.-Mexico border in recent years in a bid to beat ramped-up security at ports of entry and the rugged spaces in between. Nearly all of them linked cities on either side of Mexico's border with California and Arizona.
Tijuana is the principal gateway for drugs entering California from Mexico. Last year, authorities uncovered two large tunnels linking the gritty industrial city with the strip flanking the border south of San Diego.
Measuring around 2,000 feet in length, they were equipped rail systems, lighting and ventilation, and each discovery yielded multiple tons of marijuana.