Just before midnight, Helton was shot multiple times at the Gravity Room at 3251 Scott St., according to a fire dispatcher.
Officers located Helton, and he was transported by ambulance but died a short while later, San Francisco police spokesman Officer Albie Esparza said.
Police have yet to develop a solid description of the suspect, Esparza said, but they are possibly looking for a black male in his early 20s.
Police plan to review surveillance footage, if available, to get a better description.
Anyone with information about the homicide is asked to contact San Francisco police by calling the anonymous tip line at (415) 575-4444 or (415) TIPS-411.