Agents spotted the white truck with U.S. Fish and Wildlife Service decals along a boundary fence in Douglas, Arizona, on Monday, while responding to reports of possible drug smuggling. When agents tried to contact those inside, the vehicle suddenly stopped and two people fled into Mexico.
Agents say they found 3,200 pounds of marijuana stashed in the truck worth an estimated $1.6 million.
Smugglers have used catapults, tunnels and panga boats to get drugs across the U.S. border.