Everyone in the building was evacuated and seven crews were on scene fighting the fire.
Clouds of smoke are blowing through Sydney's CBD following a large fire at Circular Quay.
The cause of the blaze is not yet known, but several witnesses reported hearing bangs and explosions, and one witness told Ten Eyewitness News officials evacuating the area said the cause of the fire may have been a gas leak.
Here's more video of the fire, which appears to be mostly in the protective scaffolding on the building.
Emergency crews react to the Circular Quay fire.
Shareholders will give final approval for the sale in March this year.
Fire breaks out at a construction site in Circular Quay.
But as a developer the highest standards of workplace safety were expected, a Yuhu Group Australia spokesman said.
So far, there are no reports of injuries, and the fire is now under control, but the footage circulating on social media from earlier this morning is pretty dramatic.
Sarah Halliday was on her way to work when she saw the flames.
Train services were also disrupted, but have now returned to normal, and ferry services continue to operate normally.
Paramedics treated people for potential smoke inhalation but none needed to be taken to hospital, the NSW Ambulance Service said.
With regards to public transport, buses are no longer diverting but are delayed up to 15 minutes through the area.
The nearby Cahill Expressway and Circular Quay train station have both been closed while crews battle the blaze.
- Sunrise (@sunriseon7) February 12, 2018HUGE FIRE: Pitt Street near Circular Quay.