Police say the students knocked the janitor to the ground and stole her cell phone.
San Francisco police are looking for witnesses to an apparent hit-and-run Sunday evening near Fisherman's Wharf that left a pedestrian dead.
Police spokesman Sgt. Wilfred Williams said the man was found at about 6 p.m. near the intersection of Bay and Kearny streets with injuries consistent with being struck by a vehicle.
The man, who was in his late 60s, was later pronounced dead at the hospital, Williams said. His name has not yet been released.
Anyone with information about the incident is asked to call police. Those wishing to remain anonymous can call the confidential tip line at (415) 575-4444.