Police said a white Ford sedan driving north in the southbound lanes crashed head-on into a black BMW SUV about 2:38 p.m. in the #4 lane.
The BMW's driver, a 54-year-old San Francisco woman whose name was withheld by police, was pronounced dead at the scene by emergency personnel, the CHP said.
A 14-year-old boy, who was in the front passenger seat of the SUV, was taken to Stanford Medical Center with major injuries, the police said. His name was not disclosed.
The driver of the Ford, Constellatia A. Martin, 24, of Campbell, was arrested and taken to Stanford Medical Center with major injuries, police said.
Police say that it is unknown if drugs or alcohol were involved at this time.
Bay City News contributed to this report.
Stay with ABC7 News for the latest details on this developing story.