Law enforcement officials claim the weed holds a value of around $500,000.

Butler County Sheriff Richard Jones told the media on Wednesday the Fairfield stop of a tractor-trailer led officers to conduct a detailed search — leading to the discovery of nearly 600 pounds of cannabis in a "hidden well" built into the vehicle's walls.

"It took [the suspects] about six hours to get the dope out of the back of the tractor trailer and into the U-Haul," Tim Reagan, Resident Agent in Charge of the Cincinnati Office of the Drug Enforcement Agency, told local NBC affiliate, WLWT.

Officials said undercover agents and sheriff's deputies observed the group's activities for six hours before swooping in to make arrests.

"They got into the semi truck, and at that point, the doors were locked," the sheriff explained. "They were inside, taking the walls apart inside the truck. At that point, the doors were opened, the marijuana was put into the U-Haul truck, and at that point, there was a stop made in Fairfield."