The suspect reportedly entered a bank in the 3800 block of 24th Street near Church Street at about 4:05 p.m. Tuesday, San Francisco police Officer Gordon Shyy said.
The suspect, described as a black man in his late 20s or early 30s, was wearing a black hooded sweatshirt, blue jeans and black and white shoes at the time of the robbery.
Shyy said the man simulated having a gun and handed a note to the bank teller demanding money.
The bank teller complied and the suspect fled on foot with an undisclosed amount of cash, Shyy said.
No injuries were reported in the robbery, he said.
Police are also seeking information about a man who robbed a bank in the city's Financial District just a couple hours prior to the robbery in Noe Valley.
In that incident, a man carrying a red bag entered a bank in the first block of Montgomery Street near Stockton Street at about 12:55 p.m. He too approached a bank teller with a note demanding money, Shyy said.
That suspect also simulated to the teller that he had a handgun in his pocket and the teller complied with his demands, handing him an undisclosed amount of cash, Shyy said.
The man stuffed the money into the red bag he was carrying and then fled from the bank on foot, according to police.
Shyy said that suspect remains at large and is described as a white man in his early 50s who was wearing a gray shirt at the time of the robbery, police said.
Anyone with information regarding either bank robbery is asked to contact police at (415) 575-4444 or to text a tip to TIP411 with "SFPD" at the start of the message.