The investigation into an ATV crash south of Aylmer, Ont. that has left a nine-year-old boy in critical condition continues.

Elgin OPP Const. Troy Carlson says, "When we look at an investigation like this we have to look at the circumstances surrounding you know how did the kids come to be operating the ATV? Were they being supervised? You know, so that's all part of the investigation, to look at you know 500 cc - it's a fairly large ATV."

Five children were riding on a 500cc Suzuki all-terrain vehicle in the backyard of a home on John Wise Line on Monday evening when the crash occurred.

According to police the driver, a six-year-old girl, was attempting to turn a corner when she accidentally pressed the throttle, lost control and collided with two pine trees.

A nine-year-old boy who was a passenger on the ATV struck a tree and became trapped between the ATV and the tree.

Family members who had been on the other side of the home for a function rushed to the scene and freed the child, who had been knocked unconscious.

He was airlifted to a London hospital where police say he remains in intensive care on life support.

The other children on board, including the driver and a two-, four- and another nine-year-old boy were not injured, although none were wearing helmets or other safety gear.

Police say charges are pending in the collision.

OPP are reminding people to be safe when using ATVs. As of mid-June there had been nine fatal ATV incidents in Ontario in 2015.