A boy was attacked by a teenager who was part of a large group near Corby Technical College last Thursday afternoon (April 2).
The attack took place in Cottingham Road between 4 and 4.30pm, when the boy was confronted by large group of young people and assaulted by one the group.
The boy suffered facial injuries which required treatment at Corby Minor Injuries Unit.
The main offender is described as white, aged 15 to 17, about 5ft 10in with a stocky build.
He had black hair and was wearing a black coat.
Witnesses, or anyone with information, are asked to phone Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.