The police closed down the party about 11.15pm and patrolled the area after the closure.
They were alerted of the fire about 2.40am.
The dead girl's body has been taken to Auckland for a post mortem examination to be carried out tomorrow.
Detective Senior Sergeant Graham Perks said: "With the assistance of the Fire Service we have now finished examining the scene and returned the property to its owner. Although that aspect of the work is complete it is still premature to comment on the cause of the fire and whether or not it is suspicious.
"There are still a number of enquiries to make and we need to speak in detail to those who were at the premises when the fire occurred before reaching any final conclusions. We are also still keen to speak to anyone who was at the earlier party who may have information useful to the investigation." Police will be not in a position to name the person who died in the fire until she has been formally identified.
Specialist fire investigator Stu Bootten said two fire crews attended as well as operational support and specialist fire investigators.
Mr Bootten said the fire was well involved by the time the crews arrived and they could see the smoke from the station just a few streets away.
Of the six teenagers taken to Rotorua Hospital, four suffered smoke inhalation and two suffered burns.
One of the group, a 17-year-old male, has been transferred to Waikato Hospital with burns to his face, chest and arms. He is in a critical but stable condition.
Five male teenagers were also taken to Rotorua Hospital for minor injuries after the disorder when police initially broke up the party.
Police want to hear from anyone who was at the building Saturday night or early hours of Sunday morning who may have information that might assist the investigation.
Anyone with information about this fire is asked to contact Rotorua Police on 07 348 0099. Alternatively information can be provided anonymously via Crimestoppers on 0800 555111.
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Earlier story: A teenage girl has died and several others have been seriously burned by a fire in a Rotorua industrial building where police had earlier shut down a party of more than 100 people overnight.
The girl's body was found by firefighters called to the Riri St building about 2.40am today.
Six other teenagers were taken to Rotorua Hospital, including a 17-year-old boy with burns to his face, chest and arms. He has since been transferred to Waikato Hospital.
The other five teenagers were treated for smoke inhalation and burns.
Police are investigating at the scene and say it is yet to be established whether the fire was suspicious.
Officers had closed down a party in the industrial building after finding more than 100 people in the property about 11.15pm.
There had been reports of disorder as the party spilled onto the street and police said "it was clear that fighting had recently occurred".
"A decision was made by police to close down the party. Police shepherded people away from the area and a number of arrests were made for disorderly behaviour," police said in a statement.
Five male teenagers were treated at Rotorua Hospital for minor injuries suffered during the disorder.
Police continued to patrol the neighbourhood after shutting down the party and said "the area remained quiet".
There was "a small number of people" in the building when the fire started about 2.40am.
The teenager killed is believed to be a local girl.
Police said they were still contacting families and "no further details of the girl will be released until police are able to confirm the identity and all family members have been informed".
Police have appealed for information from anyone who was at the building last night or in the early hours of this morning.
Anyone with information should call Rotorua Police on 07 348 0099 or Crimestoppers on 0800 555 111.
