Sheriff's deputies responded to a home on Sigman Street shortly after 10:30 p.m. Sunday, according to the Los Angeles County Sheriff's Department.
The 5-year-old boy was pulled from a swimming pool and rushed to the hospital.
The L.A. County Sheriff's Department said the boy did not survive.
Homicide detectives also responded to the home for an investigation, the agency said.
No further details were immediately known.