Up to £20,000 worth of mobile phones were stolen during a robbery.
It happened at the Carphone Warehouse on Princess Parkway, West Didsbury, at about 5pm on 19 November 2011.
Three men with their faces covered burst into the store through the main entrance on Princess Parkway and demanded staff and customers get down on the floor and not move.
Two of the offenders then went into the back of the store and begun to fill bags they had brought with them with the phones.
The third offender remained in the shop and stole two mobile phones from customers and another from a member of staff. At least one of the customers described this man as saying: 'Don't make me shoot you' and 'don't think about being a hero' and lifted his top up to show what appeared to be the handle of a black gun.
His two accomplices then came back into the store and the trio stole a small amount of cash from the till before fleeing towards Mersey Crescent.
The first man is described as being dark skinned, about 6ft tall, of a stocky build, in his early 20s. He was wearing dark clothing with a red stripe down the leg of his trousers and a balaclava.
The second and third man were also dark skinned, about 5ft 8in tall, of a slim build, in their early 20s and wearing dark clothing and a balaclava.
Police are now appealing to anyone with information to come forward.
Detective Constable Neil Tate, of West Didsbury CID, said: "These men have stolen thousands of pounds worth of mobile phones, and in doing so put staff and customers at this store through an ordeal no-one should ever be subjected to.
"The fact that one of the offenders threatened to shoot those inside gives you a picture of how scary it must have been for those involved.
"That is why it is so important we trace those responsible and bring them to justice.
"I want to appeal to anyone who has information to come forward. £20,000 worth of mobile phones is a lot of goods and I want to urge people to be on their guard against anyone who offers them cheap mobile phones. Unless they are a licensed dealer, please do not buy a mobile phone from someone and call us immediately as this could be vital to tracing the offenders."
Anyone with information should call West Didsbury CID on 0161 856 6090 or the independent charity Crimestoppers, anonymously, on 0800 555 111.