It happened at a bank in Birmingham Street at around 8.45am on Thursday.
A spokesman for West Midlands Police said: "We are urgently appealing for information after a robbery at a bank in Oldbury this morning.
"Four people arrived at the bank on Birmingham Street at around 8.15am in a white Skoda Fabia. They waited until around 8.45am when staff arrived, and three of the men then forced their way into the building, throwing two members of staff to the floor.
"Staff members were threatened and forced to open the tills, before the group of men left in the Skoda with a large quantity of cash."
The spokesman added: "The Skoda, which was displaying the false number plates of DU12 MRX, travelled along Birmingham Street and onto Church Square. Fortunately the staff were not seriously hurt, but understandably are very shaken up by this nasty ordeal.
"The men have been described by witnesses as black, and speak with a local accent. If you recognise this car, or the people pictured, or have any other information regarding this robbery, please contact us via Live Chat on our website or by calling 101."
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org quoting crime reference number 20/499174/22.