Police said that a stolen car collided and killed two women in the South neighborhood, and the driver, a released thief, was arrested after he fled.
Police said the car, which was reported stolen around 4 p.m., hit a car and then two women, one of whom died at the scene.
The other woman died in hospital.
The San Francisco Chronicle citing Matt Haney, a San Francisco superintendent, reports that he believes one woman is 70 years old and the other is in her 20s or 30s.
Police said the suspect, a 45-year-old San Francisco resident, left the car after the accident and ran to a nearby commercial building where he was arrested within minutes.
His name was not immediately revealed.