(CNN) -- A nondescript white warehouse building in southern California hid a sophisticated drug smuggling tunnel that traffickers used to transport tons of marijuana from Mexico into the United States, authorities said.
Investigators on both sides of the border seized more than 14.5 tons of marijuana in connection with the tunnel's discovery this week, U.S. Immigration and Customs Enforcement said in a statement Wednesday.
Authorities said the drugs had a street value of more than $25 million, CNN affiliate KGTV reported.
"I'm confident that if these cartels want to continue to try to smuggle their drugs into the United States in this fashion, we're going to find them, and we're going to find them faster than they can build them," said William R. Sherman, acting special agent in charge for the Drug Enforcement Administration in San Diego.
From the floor of the San Diego warehouse, authorities found a 3-foot-wide tunnel that stretched the length of four football fields and was equipped with structural supports, electricity and ventilation, ICE's statement said.
Highway troopers found 3 tons of marijuana packed into boxes inside a cargo truck that they stopped after it left the San Diego warehouse. That discovery allowed agents to obtain a warrant to enter the warehouse, the statement said, where they recovered 6.5 additional tons of marijuana. Mexican authorities later seized at least 5 tons of marijuana from a warehouse in Tijuana, Mexico, on the other end of the tunnel.
Sherman said it was the third sophisticated cross-border tunnel found in the area within a year.
U.S. federal authorities have found more than 75 cross-border smuggling tunnels in the past four years, most of them in California and Arizona, according to ICE.