FOND DU LAC, Wis. (AP) — Authorities say a fire that killed three residents of a Wisconsin group home was likely accidental and caused by smoking materials that were improperly discarded.

The Fond du Lac Fire Department released the preliminary findings of its fire investigation on Tuesday.

Three people died in last Thursday’s fire at a home for intellectually disabled people in the eastern Wisconsin city of Fond du Lac. They were identified as 24-year-old Taylor Lavallee, 53-year-old Lisa Eastham and 72-year-old Donna Frederick.

Two other residents escaped from the burning home. Officials have said the home is for adults who can care for themselves, but have cognitive disabilities.