It was around 6:45 p.m. on Sunday when officers, conducting surveillance detail in the area of State Road and American Drive, noticed a suspicious tractor trailer.
A few minutes later, the officers said they saw two men, who were "acting very suspicious," get in the truck.
The truck was stopped in the 3700 block of Street Road for a traffic violation and placed out-of-service for safety violations.
During an inspection, a police K-9 gave a positive indication for drugs. During a search, police said they found 15 kilograms of heroin and 20 pounds of methamphetamine.
The driver, 35-year-old Estaban Zalazar Velasco of Galt, California and his passenger, 48 Juan Ledesma-Nolasco of Livermore, California were arrested.
Both were arraigned and ordered to be held on $1 million bail.