Boys as young as nine were involved in a violent robbery that left a man in hospital.
The 58-year-old victim suffered broken ribs and required further hospital treatment after the gang of boys between nine and 15 attacked him.
He was struck from behind and knocked to the ground where the group continued to assault him before stealing his bag in Milton Keynes around 9.55pm on Monday.
Detective Constable Katrina Walmsley, from Thames Valley Police, said: "The group cowardly attacked the victim from behind and then continued to assault him as he lay on the ground and tried to get up.
"The offenders are between about nine years old to about 15 years old
"Unfortunately there are not other descriptions of the offenders at this time but I am confident that someone knows who they are."
She added: "This was a traumatic incident for the victim who sustained cracked ribs and severe bruising to his face and body."
The bag was described as "distinctive," being blue in colour with white and blue drawstrings.