The incident was reported at 13:45 BST on Saturday.
The Air Ambulance Northern Ireland airlifted the boy to the Royal Belfast Hospital for Sick Children where he is in a stable condition.
The callout was the first mission for the helicopter and its crew.
The air ambulance team is currently working through final preparations including training and familiarisation flights ahead of an official media launch of the service planned for early August.
However as a result of the serious nature of the incident, the aircraft was tasked to bring the Helicopter Emergency Medical Service (HEMS) doctor and paramedic to the scene.
Glenn O'Rorke, the operational lead for HEMS, said that the service will provide a doctor-paramedic team, for the whole of Northern Ireland, which will provide rapid interventions at the scene of where people have been injured before transferring patients to the appropriate hospital.
"It will make a huge difference to patients' lives and their outcome, it will improve their quality of life after injury because we will be there in a very short period of time," he said.
The campaign for the HEMS was begun by the late Dr John Hinds.
Northern Ireland was previously the only part in the UK without such a service.
An 11-year-old boy has been seriously injured following an incident involving a tractor in the Castlewellan area of County Down.