The victim, identified by the medical examiner's office as Neilson Bates, was shot on San Bruno Avenue near Paul Avenue at about 3:30 p.m. Tuesday, Officer Albie Esparza said.
The suspect, described only as a black man in his 20s, came from behind Bates and opened fire, striking him multiple times, Esparza said. The shooter then ran away, possibly getting into a white Toyota that was seen leaving the scene, he said.
Bates, a San Francisco resident, was taken to San Francisco General Hospital where he was pronounced dead at 4:50 p.m., Esparza said.
No motive for the shooting had been established as of this morning, he said.
The homicide is San Francisco's 28th so far this year. At the same point in 2010, there had been 24 homicides in the city, Esparza said.