The incident occurred just before 9:55pm yesterday, Tuesday 10 August, at the McColls newsagent in St Johns Close.
Two males have entered the store, one suspect armed with what is described as a firearm and the second with a truncheon-style baton, and threatened staff before demanding money from the till.
They then left the premises on foot with a quantity of cash. Members of staff were left shaken but were not injured in the incident.
The first suspect is described as was wearing beige chinos, a black long-sleeved top, brogue-style brown shoes and gloves.
The second suspect is described as wearing all dark clothing, black trainers, a black puffer jacket with white zip and black gloves.
Both suspects are described as approximately 5ft 10ins in height, between 25 and 30-years-old and of skinny build. Both were wearing a stocking over their head and face, and camouflage paint on their faces.
Enquiries are ongoing and anyone who saw any suspicious behaviour, who may have been driving in the area at the time of the incident and who has dash cam footage, or has further knowledge of the robbery that could assist should contact Bury St Edmunds CID on 101, quoting crime reference 37/43915/21 via