The boy is thought to have been shot by his four-year-old neighbour after the two were reportedly playing with a gun, though a spokesperson for police in Washington, US, said they do not have any information about the gun or where the children got it from.

The Snohomish County Sheriff’s Office in Washington said the three-year-old’s father had heard a loud noise from the bedroom of the family’s home in Lake Stevens.

The father claims he found the door of the bedroom locked when he tried to enter it, but forced it open. He said he found his son with a mouth wound, but thought the injury had been caused by the door striking the child when he forced it open.

But when the child was examined at Providence Medical Centre, doctors discovered it was a gunshot wound and the boy was flown to Harborview Medical Centre in Seattle.

Detectives have said the circumstances of the incident remain under investigation.

They said the four-year-old may have accidentally shot the three-year-old, but it was not yet clear who owned the weapon, whether it was left unsecure or not or what had led to the gun being fired.

Authorities said both families are co-operating with investigators.

(the independant)