Staff at a convenience store in Bury were held up - first at knifepoint and then gunpoint - during two robberies in the space of just a week.
Police are investigating whether the same man was responsible for two robberies at the Mace Convenience Store in Brandlesholme Road, Bury.
The first took place at about 9.40pm on February 4 when a masked man carrying a knife demanded cash from the terrified shopworker before stealing money from the till.
He is was wearing a black and green camouflage tracksuit, a black balaclava and black gloves.
Then yesterday at about 9.40pm, the shop was hit again.
This time, the thief lay in wait as the shopkeeper was closing up.
As the last customer left, he ran to the front door and snapped the handle out of shopkeeper’s hand.
The thief then produced the gun and wrestled the shopkeeper to the floor outside the shop.
He then went inside and stole cash from the till before fleeing.
He was white, muscular, about 6ft tall and wearing a grey hooded top with a distinctive pattern on both elbows and across the chest.
He was also wearing blue tracksuit bottoms with three stripes down the side, black trainers and a black balaclava.
Police have now released a CCTV stills of the offender from both robberies and are appealing to anyone who recognises him, or has information about either robbery, to come forward.
Det Sgt Ian Partington said: "Both of these robberies were audacious acts committed by criminals intent on causing as much fear and intimidation as humanly possible.
"The second robbery was particularly nasty as the shopkeeper was physically assaulted and dragged to the floor whilst having a firearm pointed at him.
"If you put yourselves in the shoes of the staff at this store for one moment, you can only imagine how traumatic it must have been to be confronted by men brandishing dangerous weapons.
"For it to have happened twice in seven days only compounds how frightened the staff must have been.
"Clearly we are investigating whether one offender is responsible for both robberies and at this stage we cannot rule out anything it could be the work of one desperate man or a copycat.
"What we can be certain of is that Greater Manchester Police, and indeed the community as a whole, must protect people who work in our local shops who should not have to suffer such violence in the workplace.
"I want to reassure people living and working here that crime figures show the number of robberies in Bury has fallen by more than 25 percent in the last year.
"We are intent on keeping up that good work so we can deliver more and more reductions and keep our business community safe.
"But we know that a fall a crime is of little comfort to the staff at the Mace Convenience Store and that is why we do pursue every line of inquiry to find the culprits.
"I would urge anyone with information about either robbery to come forward.
"I cannot overestimate how important it is you call police if you know something. Don't dismiss it as trivial as could be crucial to us."
Anyone with information is asked to call police on 101 or the independent charity Crimestoppers, anonymously, on 0800 555 111.