The shooting was reported at a mansion on Mulholland Drive, north of Beverly Hills.
Upon arriving police discovered several fights in progress, cars speeding away and injured people in the street. Officials say at least four people were injured with gunshot wounds and transported to a hospital.
An investigation into the shooting is underway.
Hours before the incident police responded to the party after receiving several disturbance calls. Police did not break up the party and did not enforce the county’s health order banning large gatherings. They did issue parking tickets to cars lined up and parked illegally outside the mansion. Some cars were even towed.