Staff Lloyds Bank in Newmarket were threatened with a weapon this afternoon when a man wearing a balaclava entered the building and demanded cash.
Police were called to the bank, on High Street, at around 2.45pm and an investigation is ongoing.
It is not yet clear if any money was stolen in the incident.
The offender is described as wearing a black balaclava and dark coloured jeans.
He ran out of the rear of the bank into Fred Archer Way.
No-one was injured during the incident.
Geoff Siddons, who works in Tindalls Art and Graphics next door to the bank, said: “First thing we knew about it was when a very distressed lady came in to our shop saying she had just seen a man with a gun going into Lloyds Bank.
“Very quickly we had a large police presence outside the shop and round the back. The armed police were here in numbers incredibly quickly.
“I would say they were very nearly the first police on the scene and since then they have stayed at the bank.
“After the police arrived we just tried to calm everyone’s nerves and collect ourselves.
“We have restricted access out the back at the moment where most of the police are. They have scene of crime officers there now.”
Mr Siddons, who was upstairs in the shop when the robber arrived, added: “Our staff here handled it very well, it was probably very scary for them.”
Police are appealing for any witnesses or any with information to call Bury CID on 101 quoting crime 217 of today, 12 November.
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