The causes of two fires in Chatham-Kent earlier this week are now being ruled as undetermined.
The blazes happened in Harwich and Bothwell Tuesday night.
The first fire was on Maynard Line around 10:30pm. Then, just before midnight crews from Bothwell attended another house fire on Elm St.
Chatham-Kent Fire and Emergency Services originally blamed the house fire on Maynard Line on a window air conditioning unit that was plugged into old knob and tube wiring.
However, they say upon further investigation they can't confirm that electrical deficiencies or air conditioner units are at fault.
Total damage caused by both fires is estimated at $140,000.
An elderly resident on Elm suffered smoke inhalation.
