Firefighter-paramedics responded about 4:30 p.m. to report of three males in medical distress at a house in the 37500 block of 17th Street East, a spokesperson for the Los Angeles County Sheriff's Department said.
The firefighters arrived to find several people down and contacted the Sheriff's Department. Deputies responded to the scene and confirmed that four people were dead inside the single-story home.
The deceased men were not immediately identified, but sheriff's deputies say two of the men were in their 30s, another was in his 40s and a fourth victim in his 50s.
The Sheriff Department's Overdose Response Task Force was at the scene investigating the deaths.
No children were found inside the house.
The causes of death were under investigation.
Neighbor Susan Pokorny says she's known the occupants of the home for years.
"Our children grew up together and we moved in together, so we're fairly close," Pokorny said.
Authorities say they're not sure how the victims are related.