U.S. Customs and Border Protection officers made the biggest fentanyl bust in U.S. history at the border crossing in Nogales, Arizona, last weekend.

>> Read more trending news

Officers seized 254 pounds of the potent synthetic opioid blamed for a majority of overdose deaths and another 400 pounds of methamphetamine for a combined worth of some $4.6 million, according to Tucson.com.

The drugs were hidden in a tractor-trailer loaded with produce, which was pulled over for a secondary inspection after agents noticed irregularities in the trailers’ floor, the news site reported.

The driver was arrested and charged with two counts of possession with intent to distribute.