The Special Investigations Unit says the boy was taken to Brampton Civic Hospital for treatment of a broken leg Monday morning after being hit by a Peel Regional Police cruiser.
Police say two cruisers were responding to a call on Moregate Crescent, near Dixie Road and Bovaird Drive East at about 8:45 a.m. when one of the cruisers struck the child.
The watchdog agency has assigned five investigators, two forensic investigators and a collision reconstructionist to probe the circumstances of the incident.
Anyone who may have witnessed the incident is asked to contact the investigators.
The SIU is an arm's-length agency that investigates reports involving police where there has been a death, serious injury or allegations of sexual assault.