Police were notified around 9 a.m. that a hold-up alarm had been activated at the bank at 600 Las Gallinas Ave., police spokeswoman Margo Rohrbacher said.
A man had entered the bank and demanded cash from a teller but did not show a weapon, Rohrbacher said.
The man, described as white and in his 40s or early 50s, left through the front door on Las Gallinas Avenue. He was wearing a black jacket, dark-frame eyeglasses and a black baseball cap with writing or a logo in front, Rohrbacher said.
The bank robbery spree police believe is linked to Wednesday morning's suspect dates back to December 2012. The robberies occurred in Greenbrae, Mill Valley, Corte Madera, San Anselmo and San Rafael, Rohrbacher said.
Anyone with information is asked to call San Rafael Police at (415) 485-3000 or Crime Stoppers at (800) 222-8477.
The FBI has offered a $2,500 reward for information leading to the arrest and conviction of this bank robber. Information can be left on the FBI's confidential tip line at (415) 553-7400.
(ABC7 News contributed to this story)