Police are calling for witnesses after a man went into Eden Bookmakers in Harmanswater Road just before 8pm yesterday (Wednesday), brandishing what is believed to be a handgun.
He threatened a 25-year-old female staff member with the suspected weapon and forced her to hand over cash before he left the building.
Detective Sargent Steve Witts, who is investigating the incident, said: "This was obviously a very frightening incident for the woman but fortunately she was not hurt in the robbery.
"There would have been people in this area at the time as there is a pub and takeaway food outlets nearby and I am keen to hear from anyone who saw someone acting suspiciously either before or immediately after the incident."
The offender is white, 6ft, with a stocky build and was wearing a black balaclava and cream jacket.
Call Det Sgt Witts on 101 or Crimestoppers anonymously on 0800 555 111.
Did you witness the event? Email as at firstname.lastname@example.org