The shooting happened around 1 a.m. at a club called MyStudio on the 6600 block of Hollywood Boulevard.
Authorities said the shooter got away before police arrived. The victim was hit in his upper body and was rushed to the hospital in critical condition. No suspect information was immediately available.
"We were in the club, we heard the shots, everybody hit the floor. It was crazy," said club-goer Michael Lewis. "People were falling. It was pandemonium."
It is unclear what led up to the shooting. Police said officers never had any problems with the club in the past. Investigators are looking into whether gangs were involved.
Anyone with information was asked to call the Los Angeles Police Department's Hollywood station at (213) 485-4302.