A 16-year-old girl was walking along Kettering Road in Northampton when she was assaulted.
The girl was walking with her friend towards Morrisons on Tuesday when they were approached by a group of people, including a woman with a buggy, a teenage girl and two young children.
The group became abusive towards the 16-year-old, resulting in the teenage girl from the larger group slapping her. The group then walked off towards Morrisons.
The offender was aged about 16, of slim build and wearing a black coat with a white fur trim, blue tracksuit bottoms, blue top and red/brown hair.
The incident happened between 5.15pm and 5.45pm on Tuesday (May 10).
Officers would like to speak to anyone who may have witnessed this incident or who may have any information regarding it.
Witnesses or anyone with information about this incident can contact police on 101 or Crimestoppers anonymously on 0800 555 111.