A 13-year-old boy, who had been walking with his sister, was punched in the nose in an unprovoked attack in Darwen.
The incident occurred at the junction of Olive Lane and Sarah Street around 3.45pm on Wednesday.
Police are hunting a 30-year-old male, approximately 5ft 7in who was wearing a black jumper.
He had slim facial features, short black hair and glasses.
Anyone with inform-ation shouls call DS Ian Geogarty at Darwen CID on 01254 353841.
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