Los Angeles police received a call of shots fired at the house in the 17400 block of Devonshire Street early on Sunday (local time), authorities said. Officers arrived to find four adult victims lying face-down outside the two-storey house, they said.
No weapon was found at the scene, officials said, and no other information was immediately available about the victims.
There were multiple people in the house at the time of the shooting, authorities said, and detectives were interviewing some of the residents.
It appears that the house was an unlicensed rooming house or boarding house, said Los Angeles City Councilman Mitchell Englander, who was at the scene early Sunday. Englander's council district includes the Northridge and Granada Hills area.
The shootings in what is mostly a quiet and safe neighbourhood was shocking, Englander said. The crime scene is within walking distance of the Devonshire police station.