The 11-year-old driver of a 1993 Honda was among three Woodville residents killed Tuesday evening in a two-vehicle crash near Porterville.
Also killed were the driver's mother and 6-year-old sister.
The crash occurred around 7:30 p.m., the California Highway Patrol reported.
The Honda was eastbound on Avenue 168 when the young driver failed to stop at the Road 152 intersection, officials said.
The Honda was struck by a southbound 1999 Ford.
The 11-year-old was identified as Jose Manuel Silva Covarrubias. Maria Silva, his mother, and Elizabeth Silva Covarrubias, his younger sister, were ejected from the Honda and found in a nearby walnut orchard, the CHP reported.
"For whatever reason, the 11-year-old didn't stop at the stop sign and drove the Honda into the path of the Ford," California Highway Patrol Officer Stefanie Buck said. "It's a tragedy any way you look at it."
Another passenger, Froylon Gonzalez, 34, was flown to Community Regional Medical Center in Fresno with life-threatening injuries. He was in critical condition late Wednesday.
Felipe Zamora Gonzalez, the survivor's brother, said the family was returning from Jose's soccer-team practice when the crash occurred. He said he'd never seen the boy drive before.
Investigators had not yet interviewed Felipe Gonzalez on Wednesday afternoon to learn why the sixth-grader was driving, Buck said.
Winter fog typical of the area did not appear to be a factor in the crash, Buck said.
Dondreia Bradley, superintendent of Woodville Union School District, said she was "stunned" to hear that Jose had been behind the wheel. He came from "a wonderful family," with a supportive mother, she said.
The driver of the Ford, Charles Seguin of Porterville, was treated at the scene and released.
The Associated Press contributed to this story.
A Honda, with eleven-year-old Jose Covarrubias behind the wheel, ran a stop sign in Porterville, California colliding with a Ford around 7:30 P.M.

The eastbound 1993 Honda was sideswiped from the driver's side by a southbound 1999 Ford, killing Jose.  His sister, 6-year-old Elizabeth Covarrubias, and mother, Maria Covarrubias, were killed when they ejected, as they were not wearing seatbelts.  Family  friend Froylon Gonzalez was sent to the hospital with serious injuries, and the driver of the Ford, Charles Seguin, sustained minor injuries.

Felipe Gonzalez, Froylon's brother, said the family was returning from Jose's soccer team practice. He also added that he had never seen Jose drive before. Gonzales was the lone survivor of the Honda and has not yet been interviewed.

The accident occurred at a rural intersection and it did not appear to law enforcement that drugs, alcohol, or weather were a factor in the collision.

The bodies will be buried in Mexico near where the father lives.