The bodies of 57-year-old Manjulaben Mistry, along with 61-year-old Hashmukhlal Mistry and another 91-year-old man whose identity hasn't yet been confirmed were found on Sunday morning.
Police first responded after getting a call from a family member regarding the well-being of a relative.
That person was among the three found dead inside the home.
Peel Regional Police Const. Lilly Fitzpatrick says homicide investigators are still on the scene Monday and are still trying to piece together what happened.
She says they are speaking with neighbours in the hopes of getting more information.
Autopsies for the three dead are scheduled for Tuesday.