His father was carrying his foster son's computer, which had not been damaged, down the driveway.
"We just want to keep normality," he said.
Tauranga brigade Senior Station Officer Neil Brown said the house had suffered significant heat and smoke damage to the upper level.
He said the couple's neighbour who spotted the smoke coming from the house and called emergency services at 9.47am.
Mr Harrison said his parents were on their way to drop off donated items at the Salvation Army and they were still unsure of what started the fire.
''In a very, very short amount of time since when they left the house to when we arrived, the fire spread very fast," Mr Brown said.
Mr Brown said the owners were in the process of re-wallpapering and the smoke alarms had been removed because of this.
''If this fire started at night we quite possibly could have had a tragic outcome. I believe there are two or three children living in that house.''
Mr Brown said the incident showed how important smoke alarms were.
The house was insured.
