A teenager was injured in a “prolonged and vicious assault” outside a school.
The attack happened outside Kettlethorpe High School on Standbridge Lane, Wakefield, between 3pm and 3.15pm on Friday.
A West Yorkshire Police spokesman said the 13-year-old sustained serious facial injuries and was taken to hospital for treatment.
Anyone with information should call 101 and quote the reference number 13150161424.
Alternatively call Crimestoppers, anonymously, on 0800 555 111.