Two young boys are being held by police in South Yorkshire after a suspected serious attack on two other children.
Officers were called on Saturday when a nine-year-old boy was found in Doncaster with face and arm injuries.
An 11-year-old boy was then found in a former clay quarry with serious head injuries. He is now in intensive care at a nearby children's hospital.
Two boys, aged 10 and 11, have been arrested and police are doing all they can to find out exactly what happened.