"He wouldn't have been able to fall, technically, because you have to climb through barriers to get to the side - it's actually very safe in the building.''
About 250 workers at the site were called to a meeting after the fall and were asked to give details of where they were and what they had witnessed. They were then sent home for the rest of the day.
A witness said it appeared he fell from scaffolding on to a bin full of metal pipes.
Some onlookers thought he fell from at least the eighth floor, although a St John Ambulance spokesman said it was about the sixth floor.
A student who saw the incident initially thought the worker was dead.
"They covered him over him completely with jackets and we thought that was the end. No one did any CPR so we were pretty sure it was all over.''
"He was completely grey - all the colour had gone out of him. He had tattoos on his chest and they stood out heaps because he was so white.''
She said the workers who were first to their injured colleague took off his shirt straight away and then covered him with jackets.
"It seemed like an odd place to fall because they had been working on the other side of the building.''
A Fletcher spokesman said the injured youth had been working on the fourth floor of the building, on Mayoral Drive, but couldn't say exactly which floor he had fallen from.
"That question is part of the investigation being handled by police and the Department of Labour. We couldn't speculate.''
He said the workers were required to wear standard safety equipment at all times, including a high-visibility vest, steel-capped boots and a hard hat.
Workers use additional safety gear when working at heights.
The site would remain closed until at least today.
The construction of the building is expected to be completed by the end of the year.
FALL SURVIVORS
February 2012: Window cleaner Louisa Kuypers, 18, fell 30 metres from the roof of the Lion Breweries office building in Carlton Gore Rd, Newmarket. She was critically injured.
December 2011: Mikaela Blayney, 20, plunged six storeys during an acrobatic abseiling group's performance above Aotea Square. She broke only her cheekbone.
June 2011: A Wellington window washer fell from the fifth floor of a building and on to a car, only fracturing his big toe.
July 2010: A 15-year-old survived a 50m plunge from a balcony at the Proximity Apartments in Manukau, through a carpark roof on to a concrete floor. The teenager suffered broken bones and internal injuries.
August 2010: A North Shore 18-year-old fell seven storeys during a night of drinking and taking Ecstasy. She suffered breaks in her vertebrae, a punctured lung and three broken ribs.
