More than 50 firefighters from across Auckland have been fighting the blaze on the Whangaparāoa Peninsula, which was still burning after more than five hours.
The fire pulled crews away from responding to dozens of flooding callouts as torrential rain fell in parts of the city.
Fire and Emergency NZ assistant area commander Shaun Pilgrim said multiple calls were received from around 10 minutes before midnight.
“On arrival, the building was well involved, and the first responding units called for a third alarm.”
At one stage, 17 fire appliances, including specialist vehicles, and more than 50 personnel were at the scene, Pilgrim said.
Because the building was derelict, firefighters had only been tackling the fire defensively from outside, using handheld hoses as well as two high-reach appliances.
A Herald photographer at the scene said a specialist hose layer from Ōtāhuhu had been laying kilometres of hose to nearby hydrants and pumping water up Gulf Harbour Drive to the country club.
As the fire raged through the building, parts of the internal and external walls began to collapse, while ladder appliances blasted water from above, he said.
Police had set up cordons along Gulf Harbour Drive to keep the public back.
A spokesperson said police were making enquiries into the fire, which is currently being treated as “unexplained”.
“Enquiries by emergency services will continue this morning to determine the full circumstances. A scene guard will also remain in place until a fire investigator can attend.”
Anyone with footage or information that could help is asked to contact police on the 105 phone service, referencing job number P058799465, or anonymously via Crime Stoppers on 0800 555 111.
‘Big response’ to fire amid torrential rain, flooding callouts
Pilgrim said fire crews had come from North Shore, Manly, Silverdale and East Coast Bays, and specialist appliances from Auckland City, Avondale and Ōtāhuhu were in attendance.
The club was once a pristine golf destination, hosting two New Zealand Golf Opens and a World Cup of Golf. But it was abruptly closed last July, to the consternation of locals, and had become overgrown and derelict.