Dayton fire officials say they might never know what caused a fire that killed five people earlier this year.

The department released an incident report that lists the cause of that fire as “undetermined.”

The fire happened on North Broadway Street on March 8.

Crews searching the wreckage of the fire found five bodies.

The report said the most likely cause of the fire is trespassers inside the home using fire or a makeshift heating device for warmth.

Those flames are believed to have spread while the people slept.

The report notes the severity of the damage makes it impossible to identify where the fire started.

The report does not rule out the possibility the fire was started on purpose.