Authorities believe they've discovered a major drug tunnel that connects San Diego with Tijuana.

U.S. Attorney Laura Duffy says the drug cartels were warned about building tunnels,

"If you build them, we're gonna find them.  If we find them, we're gonna destroy them.  Today we again make good on that promise."

Duffy says the "highly sophisticated" tunnel was uncovered Wednesday night by members of the San Diego Tunnel Task Force.

Officials say the tunnel was well-lit and constructed to easily move large amounts of drugs across the border. Three people have been taken into custody.

Authorities also say they seized eight tons of marijuana and 325 pounds of cocaine.