Eight fire trucks and more than 35 firefighters battled a large blaze near Rotorua's central city.
The fire broke out at Sulphur Flats about 5.30pm and extended the city's resources. It took about 20 minutes to get under control and was out in just under two hours.
The fire was in an area of about 150m by 15m near the wastewater treatment plant fence line, off Te Ngae Rd, and Puarenga Stream.
Okareka volunteer firefighter Stuart Pinfold said a big team worked to put out the blaze.
"It's pretty much extended all of our resources in Rotorua."
Several firefighting crews attended the scene - from Ngongotaha, Okareka and the New Zealand Fire Service and staff from Rotorua Contracting (formerly Castlecorp). Police and St John Ambulance were also in attendance.
Fire Service assistant area commander Brendon Wood said a specialist fire investigator was at the scene working to determine the cause.
He said the blaze was contained within 20 minutes but because of the size of the fire, there was a lot of dampening down to do. He said there were also a couple of sulphur fires across the river that were unrelated.
"But it just goes to show the volatile nature of the terrain, that's why we can't determine the cause until we put the fire out to give someone a chance to get in safely."
The blaze occurred only minutes after putting out a smaller fire off Old Te Ngae Rd.
Cheryl Broock, who was sitting on the hill near the fire, said she lived nearby and could smell the fire.
"It is sad if it's another arson case," she said.
St John Ambulance paramedic Mike France said they were on standby because it was a major event, "mainly for (the safety) of the fire guys".
Another witness Myrin Abbott said fires always happened in the area.
"It's just part of how dry it is ... It's a decent one."
On November 8 last year another large blaze occurred in the area at Sulphur Bay. That fire took more than four hours to contain with the help of about 10 fire appliances and two helicopters with monsoon buckets. The blaze was on the lake side of Te Ngae Rd between the city and the wastewater treatment plant.
* 8 fire trucks were at the scene
* 35 personal were needed to contain the fire
* The fire covered an area of 150m by 15m