Investigators say electrical appliances, electrical systems or any mechanical or structural failures in the building were not the cause of the fire.
One student said he removed his smoke detector because it was annoying him the night before the fire.
A Bloomington apartment fire that killed an Indiana University student earlier this month is sparking questions over smoke detector safety procedures.
Renee Ohrn was killed Saturday morning when a fire broke out at Terra Trace Apartments in Bloomington.