A 15-year-old had his BlackBerry phone stolen by a gang of four teenagers.
The boy was walking through the underpass at the Queen Eleanor roundabout, towards Hardingstone, when he was approached by four teenage boys.
The teenagers pushed the victim against a wall and stole his phone. He was then pushed to the floor and the robbers walked off towards Hardingstone.
The robbery took place between 1.55pm and 2.10pm on Thursday, September 19.
The robbers are all described as white boys, aged 16-17, 5ft 6in to 5ft 7in and with a broad build. All had their faces covered and were wearing tracksuits and hooded tops.
Witnesses to the robbery, or anyone with information, can call Northamptonshire Police on 101 - alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.