A teenager was cycling along a path in Bellinge when he was assaulted by a gang who jumped out the bushes.
The boy, 13, was cycling along the path near the field next to Campion Court when males, all dressed in black Nike tracksuits, jumped out of the bushes.
Tthey surrounded him and pushed him off his bike and kicked him before running off.
All the offenders had their hoods up.
The incident happened on Sunday, May 29 between 3pm and 5pm.
Witnesses, or anyone with information, are asked to contact Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.