The incident occurred at a home in the city of Orosi located about 20 miles southeast of Fresno.
Police say 63-year-old Anthony Alvarez killed his adult daughter with her three children in the home. She has since been identified as 37-year-old Jennifer Kimble.
The father then shot and wounded a second daughter before turning the gun on himself.
Responding deputies found Alvarez dead from what appeared to be a self-inflicted gunshot wound.
The surviving daughter, 33-year-old Valerie Alvarez, was flown to a Fresno hospital and underwent surgery. She remains in stable condition.
Kimble's children were unharmed and have since been reunited with their father.
The investigation is ongoing. Autopsies are planned for later this week.
The Associated Press contributed to this report.