Police in Cambridgeshire are appealing to find a second suspect, following an armed robbery in Peterborough.
Two men entered the Londis store on Thistle Drive in Stanground at about 12:50 on Saturday.
They threatened the staff with a gun and a hammer but nobody was hurt.
The robbers took cash, cigarettes and alcohol. The quantities are not yet clear.
There are CCTV pictures showing the incident, which police are currently looking at as part of the investigation.
The shop's owner says he's very proud of his staff for the calm way they reacted.
One staff member affected said his boss had warned of the danger, following similar recent incidents across the city, and had given them training.
A man was arrested the same day and on Sunday he was charged with armed robbery. Police say they are looking for another suspect who had his face covered and was wearing dark clothing.
They warn not to approach the man. If he's spotted, the police should be called on 101.