Police are appealing for witnesses following a robbery in Northampton.
Two G4S officers were threatened by a man after they pulled up in a van outside the Nationwide Building Society between 10.45pm and 11.10pm on Thursday, January 10.
The offender threatened the men with what is believed to be a dark grey or black hand gun, and demanded they hand over a cash box, Northamptonshire Police today confirmed.
The offender then made off on foot in the direction of Towcester Road.
A spokeswoman for Northamptonshire Police said: "The offender is described as white, about 6ft, with a slim build and in his mid-20s.
"He was wearing a dark green balaclava with a bobble on the top and a dark-coloured top and trousers.
"He was also wearing dark brown gloves that looked like thick leather material with stitching on the outside."
Witnesses, or anyone with information, are asked to contact Northamptonshire Police on 101. Alternatively, they can call independent charity Crimestoppers anonymously on 0800 555111.