MALAHIDE TOWNSHIP, Ont. -- Police say a nine-year-old boy is on life support after he was pinned by an all-terrain vehicle being driven by another child in southwestern Ontario.

There were a total of five children on board when the six-year-old girl behind the wheel crashed into two pine trees in Malahide Township on Monday.

Officers say the children were driving around a backyard while their families were at a gathering on the other side of the home.

The boy was thrown and trapped between a tree and the ATV at about 8:30 p.m.

Police say family members freed the boy, who was rendered unconscious, and he was airlifted to hospital where he is now in critical condition.

The other children, ranging in age from two to nine, were uninjured though officers say none of them were wearing helmets or other safety gear.

Ontario Provincial Police Insp. Brad Fishleigh says ATVs are powerful vehicles that must be driven by skilled operators, and they are not toys for children.