The tragic incident happened at 2:47 pm at Highway 198 near 28th Avenue.
According to the California Highway Patrol, two field workers in a Ford truck were on a dirt road coming from the fields, approaching Highway 198.
Officials say they pulled out in front of a big rig that was traveling west on the highway. The impact from the crash caused them to be thrown from the truck.
The 50-year-old driver was trapped underneath the big rig and died at the scene.
His 55-year-old passenger was airlifted to the Community Regional Medical Center in downtown Fresno in critical condition.
The CHP said both men were not wearing seatbelts at the time of the crash. Officers are working to determine what led up to the crash.
The driver of the big rig suffered minor injuries and was taken to Community Regional Medical Center for treatment.