A house fire in the early morning hours Thursday at 8400 Rainbow Drive has been found to be of suspicious origin and remains under investigation, the St. George Fire Department said. 

Firefighters dispatched shortly before 6 a.m. to the scene found flames coming through the roof of the house, which was unoccupied at the time. 

The fire was brought under control at 6:47 a.m., said Eldon Ledoux, a spokesman with the fire department. 

Damage to the house was extensive, he said.