The incident was reported around 10:20 a.m. at a home in the 100 block of Crest Road East.
Deputies with the Lomita Sheriff's Station received a call from a woman saying she had found her sister and father dead. A second woman was found dead after deputies cleared the scene.
"Based on the investigators initial, ongoing investigation, this incident appears to be a domestic violence related murder-suicide, and there is no threat to the community," said the sheriff's department in an update released over the weekend.
The identities of the victims and cause of death have not yet been determined.
Anyone with information is urged to contact the sheriff's department's homicide bureau at 323-890-5500.