Sgt. Frank Preciado of the Los Angeles Police Department confirmed the shooting happened just after 2:30 a.m. in Beverly Crest, an upscale Los Angeles neighborhood.
Of the seven people who were shot, four were standing outside. The three who were killed were in a vehicle.
Their identities were not released. Those who were injured were taken to a hospital and are in critical condition.
Freciado said he did not have information on what led up to the shooting, or if it occurred at a residence.
This is the fourth mass shooting in California this month.
For the third straight year, the U.S. in 2022 recorded over 600 mass shootings in which at least four people were killed or injured, according to the Gun Violence Archive.