Three men armed with crowbars stole cash and cigarettes from a Desborough shop last night (Monday) after forcing staff to open the safe.
The incident took place at the Co-Op store in Gladstone Street at 9.30pm, just half an hour before it closed.
The men threatened staff and forced them to open the safe before making off, with a police helicopter unsuccessful in its search for the offenders.
A spokesperson for Northamptonshire Police was unable to confirm descriptions of the offenders at this stage or whether they were masked.
The spokesperson said: “Nobody suffered any injuries but staff were left very shaken.
“We are appealing for witnesses to the incident or anyone who may have seen anyone acting suspiciously on foot or in a car in the area to come forward.
“Witnesses can contact police on 101 or Crimestoppers anonymously on 0800 555111.”
The Co-Op has been contacted for a comment.