A security guard was assaulted outside the Tesco Express convenience store in Ratcliffe Drive, Stoke Gifford earlier today (Monday 28th October).
A cash box was grabbed from the guard and two suspects left the scene.
It is believed the guard was in the process of topping up the cashpoint machine at the store.
Police say they would like to hear from anyone who was in the area at the time of the incident who may have information that could help with enquiries.
They would particularly like to know whether the suspects arrived or left in a car.
Anyone able to help is asked to contact police at Staple Hill on the force number 101.
The incident was reported to the police at 1.23pm. It was witnessed by South Gloucestershire councillor Ben Walker, who tweeted:
“Cash point robbery @ #tesco Stoke Gifford. Just happened! Guard topping up cash point mugged by 2 people with a large knife.”
He later added:
“Pretty grim. All over in a minute. Looked like they either followed the van or were waiting. Well thought out.”
Police have not confirmed that a weapon was used in the incident.
UPDATE from Avon and Somerset Police (30th October): We believe the offenders left the area in a silver M reg Vauxhall Astra which was in Beaufort Crescent. Items were thrown from the car and found in Hambrook Lane.