Richard Bryant, of Tudor Green, Jaywick, near Clacton, Essex, was in a stable condition. A pellet is lodged in his skull. He was among a group playing near Clacton on Monday.
A 14-year-old boy arrested yesterday was being held in custody on suspicion of causing grievous bodily harm. Three other boys, aged 11 to 14, were being interviewed. Police recovered two air-rifles and a pistol that fires blanks.
An Essex Police spokesman said: "It was a get-together of young friends which had tragic consequences." The boys were dressed in camouflage.
Police believe that Richard may have been up a tree when he was shot. After he collapsed an attempt was made to give him first aid before one of his friends ran home to call an ambulance.
The police were called in yesterday after a scan showed the pellet lodged in Richard's head. There was an entry wound above the right ear. The pellet travelled across his skull and was wedged in the other side of his head.
He was shot at about 4pm but the emergency services were not called for some time and he arrived at hospital at 7.40pm. Police are trying to establish what caused the delay.
Doctors arranged a transfer to a specialist unit at the Addenbrooke's Hospital, Cambridge, because of the severity of the wound.
Richard's mother, Mandy, and his stepfather told police that they were unaware he had been playing with airguns.Reuse content