Four bodies were found inside a Pomona house just before midnight Thursday, but little information was immediately available on their conditions.
Officials said the discovery was made inside a home in the 2100 block of Ramsey Way, about a mile north of the 10 Freeway.
It was not immediately known how the four people died. As of early Friday, authorities also had not released information about the identities of the people, or how they were discovered.
Neighbors told KTLA-TV that a family lived at the home, which was cordoned off with police tape as investigators combed the area overnight into the early morning.
No additional information was immediately available.