Two Co-op shop workers were threatened at knife-point by a man demanding cash.
Police said the man was wearing dark clothing and escaped on a silver-coloured push bike with money from the till at the Co-op in Mansfield Road, Carrington, at 9.59pm on Sunday, June 16.
A Nottinghamshire Police spokesman said: "Detectives are making enquiries in the area and checking CCTV and are appealing for anyone who witnessed the incident to come forward."
Anyone with information which may help the investigation is asked to call the force on 101, quoting incident 880 of June 16.
Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.
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