The bodies were of a 24-year old man and a 22-year-old woman, both unidentified.
According to neighbors, the young man involved is a former marine.
Investigators spent much of Sunday at the crime scene trying to piece together what happened, when and why.
Neighbors say that the woman's mother had reported her missing, fearing that something had happened, and that is what prompted police to go to the home.
Authorities say a weapon was recovered at the scene.
"There is no immediate concern for the community, as it seems to be an isolated incident associated with what appears to be a murder-suicide," said Sgt. Edward Godfrey of the Los Angeles County Sheriff's Department.
"Seeing his brother, he's close to my age as well, and he's just in utter shock of the fact that he lost his brother and a family friend," said neighbor William Coen II.