COEUR D'ALENE, Idaho -

Coeur d'Alene firefighters are investigating the cause of an early-morning house fire.

The fire started on the 4000 block of North Royal Street around 2:30 a.m. Thursday.

Firefighters said the fire appears to be electrical and started due to a heater.

Firefighters also said the house was vacant when the fire started.

The house has minor smoke damage.