Two masked men armed with a baseball bat and what were believed two handguns entered the Metro Express store on Thornhill Road and demanded cash from the register.
They assaulted the lone member of staff during the incident just after 7.30pm on Thursday November 22.
The suspects, who both wore all black clothing and balaclavas, left empty handed and made off in the direction of Longwood Road.
The victim, a 31 year old man, was taken to hospital with what is believed to be a serious arm injury.
The first suspect is described as a 5ft 9in tall stockily built young man. He had a local accent.
The second suspect is described as a 5ft 10in tall white man with a slim build and dark coloured eyes .
Detective Inspector, Andrew Lockwood, said: “All incidents involving firearms or suspected firearms are taken extremely seriously. We are doing all we can to trace those involved.
“This incident will understandably cause concern in the local community but I would like to reassure residents that extra patrols are in place.
“Our enquiries in to this incident are ongoing and I would appeal to anyone who may have been in the area around the time of the incident who may have seen or heard anything to come forward with any information.”
Anyone who recognises the suspects described or anyone with information should contact police via 101 or by using the West Yorkshire Police 101 live chat facility, quoting 13180587120.
Information can also be passed anonymously to the independent crime fighting charity Crimestoppers on 0800 555 111.