Derbyshire police were called to the Armitt newsagent on Smedley Street on Tuesday (August 8).
A spokesman for Derbyshire police said: “Between 7.30am and 7.45am a man allegedly walked into the shop and demanded money from the till.
“He was holding what appeared to be a firearm, potentially an imitation handgun, and threatened staff but left a short time later empty handed. The man then was seen to run along Smedley Street East in the direction of Henry Avenue.”
A 40-year-old man has been arrested on suspicion of robbery and has been released under investigation.
Detective Constable, Carl Buckley, who is investigating said: “We would particularly like to speak to any witnesses who may have seen the man in the times leading up to or after the offence has taken place.
“I would like to speak to anyone that was on Henry Street, Lime Tree Road, Chesterfield Road or New Street in Matlock between the times of 7.10am and 8.00am that morning.
“If anyone was driving along these streets during those times and has dashcam footage I would also like to speak to them.”
Witnesses or anyone with information can call DC Carl Buckley on 101, quoting reference 17000337881.
Alternatively, send him a message online by visiting the ‘Contact Us’ section of the police website at: www.derbyshire.police.uk/Contact-Us.
You can also call Crimestoppers on 0800 555 111.