The man entered the Bank of America branch at 400 El Camino Real at about 1:20 p.m., passed a teller a note demanding money, and told her to hurry, Burlingame police said.
He lifted his shirt to show the handle of what appeared to be a handgun tucked into his waistband, but when another employee approached the teller, the suspect ran out of the bank without taking any cash, according to police.
He was last seen running east toward Chapin Avenue. No one was injured in the robbery.
The suspect is described as a white man in his 50s, about 6 feet tall with a thin build. He has shoulder-length hair -- which police said may have been a dreadlock wig -- and was wearing a gray beanie, glasses and a plaid shirt.
Police are asking for the public's help in identifying the man, and today released images of him that were captured by the bank's video surveillance system.
Anyone who recognizes the suspect or who has information about the case is asked to call the Police Department's detective division at (650) 777-4100.