The crash happened around 10:40 a.m. Thursday on Highway 99 near Franklin Road.
Officers say a 58-year-old woman from Avenal was driving a 2017 Nissan Frontier pickup truck south on Highway 99 with a five-year-old in the back seat of the truck.
A big rig traveling north lost its axle and the axle bounced over the barrier, hitting the Nissan.
The woman died at the scene.
The five-year-old was not hurt but was taken to the hospital as a precaution.
No drugs or alcohol are suspected in this crash.
Stay with ABC30 for the latest details on this developing story.