SAN LUIS, AZ (KYMA/CNN) – After a significant drug bust in Arizona, police found a 600-foot long tunnel allegedly used to smuggle drugs across the border from Mexico to the kitchen of a former Kentucky Fried Chicken restaurant.

Police conducted a traffic stop Aug. 13 on Ivan Lopez, during which they say they found hard narcotics in the trailer of the truck Lopez was driving.

Authorities found 118 kilograms of methamphetamine, 6 grams of cocaine, 3 kilograms of fentanyl, 13 kilograms of white heroin and 6 kilograms of brown heroin, according to Homeland Security agent Scott Brown.

The fentanyl alone could have supplied three million doses.

Brown said Lopez had been seen earlier that day in San Luis, AZ, removing the toolboxes in which the drugs were found from the former KFC restaurant. Lopez owned the building.

Agents executed a search warrant at the former restaurant and found the tunnel in the kitchen area. The tunnel was only 8 inches in diameter but was 22 feet deep and nearly 600 feet long.

The tunnel traveled from the former KFC to a home in Mexico, where a trap door was found under a bed.

Authorities say the tunnel was used to smuggle illegal drugs across the border and that the drugs were being pulled to the U.S. with a rope.

The tunnel is still under investigation.