A man was arrested Thursday after the Department of Public Safety seized more than 51 pounds of suspected fentanyl pills from his pickup truck.

27-year-old Alonso Martinez-Zepeda, of Sinaloa, Mexico, was involved in a non-moving traffic stop on westbound Interstate 10 in Eloy, according to a post on the DPS Twitter page.

During the stop, the DPS trooper saw several indicators of criminal activity, according to the news release. A search of the vehicle commenced, during which time troopers located the fentanyl pills concealed within the truck.

Martinez-Zepeda was arrested on suspicion of possession and transportation of a narcotic drug for sale. Investigators determined the pills, which have an estimated street value of $694,000, were being transported from Nogales, Mexico, to Phoenix.