The teenage gang used blackmail and beatings to back up their eight- month reign of terror. The breakthrough came in February, when a 13-year-old boy from Cantley, in Doncaster, south Yorkshire, made an official complaint.
Inspector Paul Cropley said yesterday: "It appeared that that was the tip of the iceberg."
Police sought the co-operation of staff at Hall Cross comprehensive school in Thorne Road, Doncaster. Letters were sent to the parents of more than 350 pupils in years 9 and 10, with ages ranging from 12 to 14.
Inspector Cropley added: "Nearly all the letters were answered and many contained details of alleged offences against their children. As a result of these complaints, many hours of inquiries began with a dedicated team of officers."
It ended this week, when police arrested 10 youths aged 13 to 15, all from the Hyde Park, St James Street and Bentley areas of Doncaster, and charged them with a total of 35 offences including blackmail, robbery, affray, assault and theft.
The youths have been released on bail to attend at Doncaster juvenile court on 19 June.Reuse content