Authorities have begun investigating the cause of a blaze that's claimed three lives. (Bianca De Marchi/AAP PHOTOS)Authorities have begun investigating the cause of a blaze that's claimed three lives. Neighbours told AAP the family, yet to be formally identified, had been living at the property for around 20 years. Officers from Campsie Police Area Command have since established a crime scene and an investigation has begun, NSW Police said. Police will work with the extended family to understand what led to the tragedy, Superintendent Sheridan Waldau said.