Ontario's police watchdog is stepping in to find out more about an incident in Innisfil that left two people injured. 

The Special Investigations Unit says just after midnight on July 7, a 51-year-old man and a 45-year-old woman were walking in Innisfil Beach Park.

Investigators say there was some kind of "interaction" between the two and officers from South Simcoe Police. The man and woman received serious injuries.

Three SIU investigators have been assigned to the case.