The remains were found Wednesday morning near the Rio Hondo bike path, the Los Angeles Times reported.
"Obviously, finding remains in an area like that is suspicious in nature," county Sheriff's Lt. Dave Coleman said.
Coleman said an investigation into the remains was ongoing and added the case hadn't been ruled a homicide.
The age and gender of the remains had yet to be determined, a coroner's official said.
Millions of Getty images now available for free via embed tool
Boston schools pull out free condoms over wrapping complaints