OAKVILLE, Ont. -- Three Oakville men are in custody after a Halton Region police officer was knocked down by a car while investigating suspicious activity.

Police say undercover officers were approaching a car in a parking lot at Trafalgar and Dundas Street Saturday evening when the vehicle lurched ahead knocking an officer to the ground.

Police say the officer fired a shot, striking the car, which stopped a short distance away.

The officer hit by the car was treated in hospital and released. No one else was injured.

Twenty five year old Jonathan Young is facing charges of dangerous operation of a motor vehicle and assaulting a police officer.

Twenty year old James Falkenstein is charged with possession of a controlled substance and 20 year old Jon Kobli faces that same charge.