MORA - Investigators believe a fire that killed three people in Mora last week was accidental.  They also say smoke alarms at the building were not working properly.

The preliminary investigation by the State Fire Marshal indicates the fire started in the living room of one of the apartments in the four-unit building.

Investigators say the hardwired smoke detectors were not working, and the battery operated smoke detectors were either removed or had their battery removed.

A father and son and a neighbor all died in the fire.  A fourth person suffered serious injuries.