Three 11-year-old boys were assaulted and robbed in Stony Stratford last Saturday (July 22).
Police are appealing for witnesses to the robbery which happened around 4pm in the grounds of Mary Magdalen tower.
The boys were approached by two older teenage boys, who threatened the victims and demanded they hand over their phones.
Three other boys were present at the time and appeared to be part of the same group.
One boy fought back and was punched a number of times before he managed to run off to seek help. Another of the victims was pushed to the ground and sustained a fracture to his wrist.
The phones were then returned to the victims.
The first offender is described as a white male aged 15 to 17, 5ft 7ins, medium build with dirty hair. He wore a hooded top with a grey hood which was up and the rest of the hoodie was blue.
The second offender is a mixed race male aged 15 to 16, with brown hair. He was wearing dark jumper and trousers with a small blue bag worn across his body.
Anyone with any information about this incident is asked to contact police on 101 quoting ref 43170217716.