Several families self-evactuated at the southern end of Piha Beach on Auckland's west coast after a scrub fire broke out overnight.
At least two fires broke out in the area. One has destroyed a takeaway shop near the surf lifesaving club.
Adey's Place manager Kim Morris told media he spent the early hours watching the fire spread, and doesn't expect to salvage much from the ruins.
"It's a very old building. A fire wouldn't take long - 10 minutes, 15 minutes - and it would destroy it just like that," he told Fairfax.
Before dawn there were 17 crews battling fires in the area, with helicopters deployed. Around 90 firefighters were on the ground.
Senior station officer Evan Lamberton says there's a long way to go before things are under control.
"It's actually becoming quite a large deployment of firefighters, most of whom in this area are volunteers."
A scrub fire at the Tasman lookout has been contained, but the larger blaze is still burning.
It follows a spate of fires police believe were deliberately lit in the area last weekend.
"These fires are a destructive and senseless act of vandalism and police will work to hold to account whoever is responsible," Detective Sergeant Ashley Matthews said on Wednesday.
"We are conducting scene examinations with the assistance of fire crews and are making further enquiries."
No one has been reported injured. Ambulances at the scene were there as a precaution in case firefighters needed assistance.
A specialist fire investigator will visit the takeaway shop fire at 10am.