The robbery was reported at 9:06 a.m. at a bank in the 1900 block of Union Street.
A suspect, described as a man between 25 and 40 years old, walked up to a bank teller and handed her a note demanding money, according to police.
The teller, fearing for her safety, handed the suspect an undisclosed amount of cash and he fled from the bank, police said. The suspect had not been found as of this morning.
Anyone with information about the robbery is encouraged to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.