Ontario's Special Investigations Unit hopes witnesses come forward as they investigate an incident in Harrow.
The agency said officers from the Ontario Provincial Police Essex detachment went to a home on Secord Avenue around 9:15 p.m on Tuesday to investigate a mischief call.
Once they found the suspect, a 26-year-old man, they arrested him, but there was a struggle, and the man suffered a serious injury.
He was taken to the hospital.
No other details have been released.
Two investigators from the SIU are looking into the case, but anyone with information can call the lead investigator at 1-800-787-8529. If you have video evidence, that can be uploaded to the SIU website.
The Special Investigations Unit investigates incidents involving police officers that have resulted in serious injury, sexual assault, or death.