A 12-year-old boy was robbed by a gang of three men in Kettering on Tuesday evening (May 20).
The child was walking his dog near a footbridge over the railway line at about 7pm when he was approached by the gang.
The footbridge, behind Millennium Drive, connects Headlands and Thurston Drive.
The men assaulted the boy, stealing his mobile phone and his skateboard.
Police say the offenders were all aged about 18 to 19. Two of the men were white and one was black.
Witnesses to this incident, or anyone with information, are asked to contact Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.