Emergency personnel responded to the crash at Van Ness Avenue and Grove Street just before 2:30 a.m. and found the pedestrian, a man in his 50s, suffering from life-threatening injuries, San Francisco police Sgt. Eric O'Neal said.
The man was taken to San Francisco General Hospital in critical condition.
Police said it appears the man was walking west in the crosswalk on Van Ness Avenue when he was struck by the vehicle, described as a sport utility vehicle, that was traveling south on Van Ness Avenue in the No. 2 lane.
The driver fled the scene and police are continuing to search for the vehicle and driver.
Officers remained at the scene of the crash as of 4:45 a.m.