A gunfight between two groups of youths erupted on the streets of Chinatown on Friday evening, injuring seven people, two seriously.
Shots were fired as one group chased another, police Cmdr. Dennis Martel said. At least one bystander, a woman four months pregnant, was among the victims.
The shooting began after five or six youths standing on a corner were approached by another group, Martel said. The first group fled, but it was not clear which group opened fire.
A 23-year-old man shot in the abdomen was listed in critical condition and a 16-year-old boy shot in the groin was in serious condition at San Francisco General Hospital.
Four others were in stable condition at the hospital, including the pregnant woman who had gunshot wounds in her back and feet, said Dr. Steven Hoffmann.