Two victims found by officers inside the nightclub were taken to a hospital for treatment. Five other victims later arrived at local hospitals with gunshot wounds, police said. Police watch commander Sgt. Ryan Wilson said none of the victims' wounds were life-threatening.
One witness who did not want to be identified told KTLA-TV that he was dancing when gunshots rang out. He said he saw multiple people firing guns and that there was a bottleneck of people trying to get out of the exit as he hid behind the bar and prayed.
The initial police investigation shows that a fight broke out at the club and those involved began exchanging gunfire both inside and outside, said Officer Ryan Railsback, a department spokesman. Investigators are looking into whether the shooting was gang-related, Railsback said.
The investigation was being handled by the department's robbery-homicide and gang intelligence units. Riverside is about 55 miles (88.5 kilometers) inland from Los Angeles.