The bomb threat was reported at the Chase Bank Building at Chester and 17th Street around 1 p.m. Tuesday.
An unidentified man entered the bank and is currently "barricaded" with an unknown number of people, according to Bakersfield Police Department Sgt. Eric Celedon.
Officers say one hostage has been released from the building and everyone else remains safe. Negotiations with the suspect remain ongoing.
According to ABC affiliate KERO, Bakersfield City Hall and Police Headquarters are among the buildings on lockdown as a precaution.
The FBI and the Department of Homeland Security are assisting.
Stay with us for the latest details on this developing story.