(CNN) Authorities in Arizona discovered $1 million in drugs during a traffic stop -- and officials say that led them to a nearly 600-foot drug tunnel that runs between a former fast food restaurant and a private home in Mexico.

It all began August 13, when police in the border city of San Luis, Arizona, say they saw the owner of a now-abandoned business bringing several plastic containers outside and loading them onto a trailer, according to court documents obtained by CNN affiliate KGUN.

Officers pulled the man over for an unspecified equipment violation. During the traffic stop, a narcotics dog alerted authorities to the presence of drugs in the two containers.

Inside the containers, police found 239 packages of various drugs, including over 261 pounds of methamphetamine, 14 pounds of cocaine, 30 pounds of white heroin, 13.7 pounds of brown heroin and 6.8 pounds of fentanyl. The fentanyl alone "translates to over 3 million dosage units," Homeland Security Special Agent Scott Brown told CNN affiliate KYMA on Wednesday.

Police listed the total value of the drugs at over $1 million.

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