UXBRIDGE (AP) — Fire officials say the cause of an apartment house fire that killed a woman and a young girl may never be determined because of extensive damage.

State Fire Marshal Stephen Coan said in a statement Wednesday that investigators have focused on possible accidental causes, but there isn’t enough evidence in the collapsed house to indicate what started the fire.

Authorities have not positively identified the bodies of the woman and child found Tuesday in the rubble. Neighbors said a 45-year-old woman and her 6-year-old daughter who lived in the house weren’t seen after the fire.

Investigators determined the fire started in their first-floor apartment Monday night

Seven other people lived in the old farm house that had been converted into five apartments. Coan said smoke alarms helped them escape safely.

Copyright 2012 The Associated Press.