Police have arrested and charged a man and a woman with arson after an early morning blaze in central Taupō.
As many as 50 firefighters were called to the fire that spread across three shops, cut power and closed a main road.
The ceilings in two shops on Tongariro St collapsed, and the blaze took crews from Taupō, Rotorua, Kinloch, Tokoroa and Ngāruawāhia two hours to control.
In a written statement this afternoon, Detective Senior Sergeant John Wilson said "A 24-year-old man was arrested in Auckland and is expected to appear in Auckland District Court tomorrow".
"A 43-year-old woman was arrested in Taupō and is expected to appear in Rotorua District Court tomorrow."
"Police are aware of speculation in the community about who was responsible for the fire".
"We can confirm that the two people arrested in relation to the fire are not the owners of the business."
Detective Senior Sergeant Wilson also said there were safety concerns regarding the structural safety of the building and asked that people stay well away.
A police scene guard will be in place overnight around the damaged shops, and the scene examination is expected to continue into tomorrow..
Fire Emergency New Zealand (FENZ) were first alerted to the smell of smoke at 1.15am .
At midday today a police spokeswoman said the cause had not yet been determined.
"That's what we will be working with FENZ to establish. It's not possible to put a timeframe on how long we will be there."
Some of the businesses affected by the fire were Taupō Sushi, Hamills Taupō, Cafe 99, Souvenir Outlet and Ridgeline of New Zealand.
There were no reports of injuries.
Assistant area commander for Central Lakes, Hamish Smith, said the fire took hold quickly, despite officers being on the scene quite early.
He said the blaze was centred within one building housing two shops, Taupō Sushi and Hamills, an outdoor clothing and goods store.
Both were extensively damaged by the fire.
Smith said crews accessed the fire via a service lane at the back of the shops.
"There was good access for fighting the fire but it developed quickly. The roof of both shops collapsed which made it difficult to fight."
At 5.40am FENZ said the fire was contained but as many as 50 firefighters were still on scene.
Police closed a section of Tongariro St from Heuheu St to Tamamutu St and motorists were urged to avoid the area.
Electricity was out for the entire block of businesses.
A Bendon outlet also sustained smoke damage through an air conditioning system.
Wayne Morris, a trustee for Mokopuna Trust, owners of the Bendon store building, said he had been trying to assess the damage this morning.
"Police have got it cordoned off, and it will be a few days while they investigate, I suspect."
Perpetual Guardian has confirmed it is a trustee of an estate that owns eight units in Taupō, including the Taupō Sushi store.
In a statement Perpetual Guardian said it was working with NZ Police to ensure the relevant authorities had the necessary information to conduct a thorough investigation.
"Perpetual Guardian is working with the affected tenants to determine the level of damage and to help ensure access is re-established for those affected as expeditiously as possible."
A business owner at The Fern Cafe on Tamamutu St said she understood the sushi shop had "extensive fire damage".
The shop next door was also affected by the blaze.
"Several businesses have had to close," she said.
The business owner said her cafe, which was located a block back from Tongariro St, was able to open as they had access to the front door, although there was no access to the alleyways behind some shops.