(CBS) — Investigators are trying to determine the cause of a fatal early-morning fire Wednesday near East Dundee.

The two-bedroom home at 15N384 Richardson Drive was engulfed in flames when police and firefighters arrived on the scene, summoned by a passerby who called 9-1-1.

Firefighters were unable to enter the home at first because of the fire’s sheer intensity, but Kane County Sheriff’s Police Lt. Pat Gengler said they were able to do so after about half an hour, where they found both victim and family dog.

Police won’t know what killed them until an autopsy Friday. The home was on the market for $118,000, but is a total loss.