California Highway Patrol officers say the 84-year-old behind the wheel was driving south on the 99 near Cleveland Avenue Tuesday evening.
A box truck in front of him came to a stop, causing the man to veer off the highway through a concrete barrier and up an embankment.
The 84-year-old then turned back to the left, going back through the barrier and crashed into the side of the same box truck.
The elderly driver died in the collision. The truck driver was not injured.
The victim is said to be from Los Banos, but he has not been identified.