The fire was under control by about 10.30pm, and a "hot spot" found at the house was doused at 11 by crews that remained on the scene until after midnight.
No other homes were damaged, the spokesman said.
The Fire Service received mixed reports about the cause of the fire, he said. "There were reports it started from the house and reports it started from a woodfire nearby."
One person who suffered burns was transported by ambulance to Christchurch Hospital in a serious condition - the ambulance was called to the scene at 7.21pm.
An investigator will be at the scene later this morning to determine the cause of the fire.