Sgt. Danielle Newman says the tourist was shot as the couple was taking a stroll through the city's rugged Tenderloin neighborhood Sunday morning.
Newman says the tourist, who police describe as a man in his 30s, heard some people yelling that was followed by a gunshot. The tourist then realized that he had been hit in the leg.
The tourist was taken to a local hospital for treatment as his injuries are considered non-life threatening. His name has not been released.
Police say one woman has been taken into custody on possible attempted homicide charges. Her name has not been released.
The incident remains under investigation.
Any witnesses are urged to contact police at (415) 575-4444, where they can leave tips anonymously.