The Idaho State Fire Marshal's office says investigators are unable to determine what caused a house fire that killed a Payette couple earlier this month.

The bodies of Phil and Darlene Skelly were found inside their home after the Jan. 2 fire.

Idaho State Fire Marshal Knute Sandahl said in a prepared statement released Monday that the fire began in the living room of the home, where a dining table was located. A hole in the floor suggests the fire may have burned for up to two hours before it was discovered by witnesses who called emergency workers.

The home was fully engulfed when firefighters arrived. Sandahl says investigators examined several potential sources of ignition but were unable to determine the cause. The fire is not considered suspicious, however.