The shooting was reported at about 9:40 a.m. at the intersection of 16th and Folsom streets, San Francisco police Lt. Troy Dangerfield said.
Two men, ages 22 and 18, had gotten off a Muni bus and were on the southwest corner of the intersection when they were approached by three suspects who opened fire, Dangerfield said.
The 22-year-old man was hit by the gunfire and was taken to a hospital with injuries that are not believed to be life-threatening, Dangerfield said.
The 18-year-old was not injured in the shooting, but a nearby parked car was struck by the gunfire, he said.
No arrests have been made, Dangerfield said.
Investigators are interviewing witnesses and will see if images of the suspects were captured by cameras on the Muni bus, he said.
Employees at the SoccerCafe, located at 2797 Folsom St., heard six shots, manager Joan Holsten said.
An employee at the nearby J. Georgie's Donuts at 2799 Folsom St. said she also heard six rounds fired.
"I saw three boys shooting, and ducked under the counter because I was scared," said the employee, Prethynu, who declined to give her last name.
Witnesses at the scene described the suspects as three black teenage boys wearing all dark clothing.