"It appears this incident is gang-related, the victim is a known gang member. He is being uncooperative with investigators at this point," Sgt. Daryl Fong said.
Police have released two suspects they had detained briefly in connection with the shooting after determining that, while the suspects were in the area of the shooting, they were not directly involved, Fong said.
Investigators are looking for a third suspect who remains at large.
The shooting was reported around 10 p.m. in the 300 block of Jefferson Street, in the same block as the In-N-Out Burger restaurant.
Police said a man pulled a gun and shot another man once during an altercation involving a small group of people.
"It appears that the victim's group initiated a confrontation with the suspect's group prior to the shooting," Fong said.
The victim was shot in his upper thigh and was transported to San Francisco General Hospital, where he is in stable condition, Fong said.
Fong said witnesses identified three possible suspects in the shooting, and police located two of them.
They were briefly detained, but were later released after police determined they were not responsible for the shooting.
The third suspect remains at large.