"We got hold of two of them, so they're accounted for, and we couldn't account for the other one," he told APNZ today.
"So whether he was inside or done a runner or something like that, we're not sure. We haven't found anybody inside as yet."
Police were today looking for the man.
Mr Johnson said the fire crews had done a great job containing the fire yesterday.
"They saved the building next door to it, which was half a metre away to a blazing building, which I thought was a good job," he said.
"One of the tactics is actually to contain the fire before we actually try to put the fire out, to stop it spreading to the next building.
"The first thing we did was contain it, and then made entry into the building to extinguish it."
A neighbouring building suffered smoke damage, melted guttering and some scorching but the fire did not penetrate it.
The cause of the fire was being investigated today.
The fire was the second in recent years after the building was set alight in 2009 while it was still occupied.
Zachariah Wilton, then 19, was jailed last February for two years and three months for starting the fire.
The wooden, three-storey, eight-bedroom, three-bathroom house has a 2009 capital value of $670,000.
