The male staff member, who had not been named as C-Store went to press, was shot several times by a lone gunman who entered the Premier Brookhouse Wines supermarket at about 9pm on Saturday, July 4.
The gunman fled the scene in a blue Mazda, which police later found burnt out. The victim was taken to hospital where he died as a result of his injuries.
Eleven people have been arrested by Greater Manchester Police in connection with the incident, on suspicion of conspiracy to commit murder. "This was a brutal attack on an innocent shopworker," said Detective Superintendent Rebekah Sutcliffe of Greater Manchester Police. "This man was just going about his work when he was gunned down."
Sutcliffe added that the police believed the incident was not gang-related. "We can speculate it was a robbery gone wrong, but nothing was stolen so at the moment we have no motive," she said.
Booker Premier sales director Steve Fox said: "We send our sincere condolences to the victim's family. We are offering any additional support that they need to help them through this time."