Fresno police say Eric Heard shot his sister 33-year-old Fanchon Moore and his 17-year-old nephew Antonio Rodriguez on Friday evening at a home on Weathermaker and Winery Avenues.
Moore was pronounced dead at the scene, while Rodriguez was rushed to a local hospital. The teen later died.
RELATED: Fresno police identify homicide victims as a mother and her teenage son
Detectives found Heard nearby the house on Friday night. He was detained for questioning. Investigators say he had been involved in an argument with Moore and Rodriguez before the shooting.
Heard has since been charged with Moore and Rodriguez's deaths. He was booked into the Fresno County Jail for two counts of murder.
Police are still working to determine what led up to the shooting. Anyone with information on the case is asked to call the Fresno Police Department.