After more than four hours, firefighters are still battling to control an inferno on top of Auckland's SkyCity Convention Centre, flames spreading to other parts of the construction site.
A worker who went on a smoko break, leaving a blowtorch unattended, is believed to have sparked a massive inferno on top of the $700 million building.
Downtown Auckland is filled with billowing black smoke - which police warn could be toxic. Nearby buildings have been forced to shut down their air conditioning systems.
Account manager Charli Farman was sitting at her desk when she noticed smoke and told a colleague "I think it's on fire".
"It was a really small amount of thick black smoke."
"Then all of a sudden it was flames and really dark smoke."
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Farman said a man in an orange construction vest was standing at the top of the building when the fire started.
"He was standing at the back for about four minutes but then he just ran when the flames started to spread".
Construction worker Sandeep Patel said he was inside the building that is now on fire and had been evacuated.
"We have no idea what is going on, all of a sudden we were told to get out."
Auckland Mayor Phil Goff is reporting what he can see live on his official Twitter page.
"Fire is really building. People can be seen on the roof,'' he wrote.
The SkyCity Convention Centre
• The $700m project is well underway, and is due to hold its first conference in October next year.
• Site: 1.4ha
• Floor space: 32,500sq m
• Equivalent to 4 rugby fields
• 33 meeting spaces of various sizes
• 5 times larger than existing NZ convention space
• Able to host events for up to 4000-plus people
• NZ's largest theatre, able to seat 2850 people
• NZICC designed by Warren and Mahoney, Woods Bagot, Moller Architects
• 303-room 12-level Horizon Hotel by Warren and Mahoney, Moller Architects