It is understood several people have been spoken to, but no charges had been laid last night.
About 8pm, Scott McCulloch heard noises coming from across the fence. From his studio flat behind his mother's house at number 86, he saw at least three teenagers at his neighbour's property and called the police.
A thin plume of smoke drifted up from the bungalow, which was wrapped in scaffolding, before a loud explosion.
Mr McCulloch told the police they had better call the Fire Service too.
His mother, Robyn, was absent so Mr McCulloch was alone in trying to save their possessions.
He managed to move his mother's car across the road but his own ute - which he needed to get to his new workplace after losing his earlier job when Mainzeal went into receivership - was destroyed.
Mrs McCulloch kept her family history in the attic. The fire tore through the roof and erupted out the other side.
"It's completely destroyed, the whole house. It'll need a total rebuild," said neighbour Jenny Davis, with whom Mrs McCulloch is now staying.
"She's very distressed."
As Mr McCulloch watched his mother's house catch fire, neighbours were doing what they could to try to stop the flames spreading.
Locky McArthur and Rebecca Treacher were watching TV two doors up from the house where the fire started. "I could see an orange glow on the fridge door ... then I turned around and saw all the smoke," said Miss Treacher, 20.
Mr McArthur ran to get the garden hose while his mother dialled 111. He jumped over the fence and sprayed the neighbour's garden to try to stop the fire.
"It was this close to getting another tree," he said.
"You could feel the heat of it."
A family rent the property he was trying to save and managed to get out, but it's likely the house will need to be rebuilt.
Yesterday, insurance assessors were at the property, boarding up windows and evaluating the damage.
The entire left side of the dwelling is blackened and burnt. Concrete stairs covered in soot and ashes lead up to a frame that was a front door until Saturday evening.
The occupants were too shaken to speak yesterday.
Yesterday morning, the owner of number 88, Mark Brooks, the contractors doing the renovation work and Mr McCulloch returned to to salvage what they could.
The builders searched the gutted house and pulled out powertools and toolboxes, undamaged but blackened.
Bob Jansen, the main contractor, said the house would need a "total rebuild". The workers hadn't been far off from finishing.
He and two of his builders were there at 7am yesterday, after getting a call from Mr Brooks the previous night.
Mr Jansen said they could see accelerant had been spilled throughout the house.
Ms Davis also returned to see just how bad the damage was in the daylight.
"It's just totally heart-breaking."
