Update: Staff and customers were evacuated from a Bankwest branch in central Perth after a man threatened staff with a knife this afternoon.
Officers were called to the bank in the new Raine Square development on Murray Street just before 2pm and cleared customers and staff from the bank.
Police said the man entered the bank armed with what is believed to be a knife and threatened staff.
It is not known how much money was stolen.
The man is described as being in his late 20s or early 30s with fair-skin and a medium build. He was wearing a black t-shirt with white writing on the front, a baseball cap and dark-coloured trousers.
Those with information are asked to contact Crime Stoppers on 1800 333 000.