Bank sources said the fire originated from an electric short-circuits on the first floor of the six-storied building around 12:15am.
Being informed, four vehicles of fire service rushed to the spot and doused the flame around 2am.
Chittagong Fire Service sources said the estimated damage caused by the fire was Tk5 lakh.
Bank sources also said furniture, computers and other documents of the bank were gutted. However, none was injured in the fire.