RAW VISION: A fire has broken out at the Barangaroo development site, engulfing the area in smoke.
4:26PM: Bevan Shields: Superintendent Krimmer said monitors had been deployed around the fire site to monitor the smoke plume.
If the monitors detect abnormal gas or toxicity levels, further evacuations will be considered, he said.
The Barangaroo site has a history of pollution and contamination.
However, an Environment Protection Authority spokeswoman has said the affected site had already been excavated, eliminating potential asbestos hazards.
4:16PM: Bevan Shields: A CFMEU site official expressed anger at Lend Lease during a press conference saying the construction company was unable to tell the union that all workers had been accounted for.
"What has happened down here as far as we're concerned is an absolute disgrace."
When asked if he doubted Lend Lease's commitment to safety he said that it was "best summed up" by recent incidents at Lend Lease construction sites in Sydney, including a crane collapse in Ultimo last year.
4:10PM: Natalie Hambly: "Our big concern is keeping the bottom of crane cool, and we are fairly confident we are being successful at that," said Superintendent Krimmer.
"We want to cool the entire structure down and that is going to use a lot of water.
"We had to pump water from a number of surrounding streets," he said.
"We are monitoring the water run-off to make sure there is no risk to the drains and harbour, but safety is our number one concern."
He estimated the crane is about 50 metres in height and said he was unable to give any time estimates.
4:00PM: Natalie Hambly:Superintendent Krimmer says he doesn't know what has caused the fire.
"We can't get into that basement here, it's too hot and smoky.
"Thermal imaging cameras aren't showing us anything at the moment."
"It's a difficult operation for our crews, it's extremely humid. We are having to rotate those firefighters regularly so it is quite a large operation."
3:58PM: Jacob Saulwick: Another transport update
Bus commuters will be allowed to use their tickets on trains and ferries, as multiple roads through Sydney’s CBD grind to a halt due to the fire.
The Transport Management Centre is advising motorists to avoid central Sydney, with the Western Distributor closed in both directions, causing lengthy delays nearby.
The long build-up of traffic already heading south over the Harbour Bridge means peak hour buses that return north over the Bridge are likely to face lengthy delays.
In addition, the Transport Management Centre says buses heading into the city via Victoria Road are already running 15 minutes late.
3.57PM: Natalie Hambly: Superintendent Ian Krimmer has given a statement to media, saying the crane is the major concern:
"Our big concern is the crane collapsing.
"Crane collapses can be quite dramatic, they tend to twist and topple over. That twist means we can't predict where it will fall."
He said firefighters were pointing laser beams to the top of the crane to keep track of any movement.
3:54PM Saffron Howden: Sixty children aged six and under are being kept indoors at a childcare centre nearby on Sussex Street.
The children's parents have been informed not to pick them up yet.
A spokeswoman for Only About Children said the childcare centre's director had emailed all parents since the fire broke out.
"Their concern is the air," the spokeswoman said. "They're staying inside."
She said there were no concerns about any danger from the crane should it topple.
3:34PM: Nick Ralston: Lend Lease said the fire broke out at 2:10pm in the south-east corner of the site.
"We evacuated the site ... and we are currently working with emergency services to put out the fire," a Lend Lease spokesman said.
"Our focus right now is to ensure the safety of our workers and the surrounding community.
"We are working with the surrounding buildings to evacuate those at risk ... There's a number of buildings that are potentially at risk.
3:33PM: Saffron Howden: Traffic diversions
The Transport Management Centre said motorists wanting to travel north from the city centre are advised to use the Anzac Bridge.
Buses heading into and out of the Sydney CBD are also delayed and passengers were being advised to allow extra travel time.
3:31PM: Fears crane could topple
Brad Fraser, who can see Barangaroo from his office block on Clarence Street, said he could see the burnt base of the crane.
"The main focus looks to be on the crane which you can see it's charred at the bottom. All the white matter's gone black," he said.
Mr Fraser said he first noticed plumes of "fairly white smoke" about 2pm, but said little was being done to evacuate workers until fire trucks arrived.
"There was a lot of inactivity, just a lot of people standing around."
3:27PM Peter Hannam: No asbestos fears, says EPA
The Environment Protection Authority said the fire is in a new building where the site had already been excavated, eliminating potential asbestos hazards.
"We don't have any concerns" about asbestos, an EPA spokeswoman said, adding that the authority would examine the accumulated water from the fire once staff were permitted on to the site.
Almost a year ago to the day, workers excavated asbestos-contaminated soil from the northern end of the Barangaroo site. The 23 asbestos fragments followed earlier findings of the hazardous material on the southern end of the Barangaroo site in April 2012.
Work was also halted in late 2012 after landfill was found to contain as much as 1 per cent bonded asbestos.
3:21PM Nick Ralston: NSW Fire and Rescue spokesman Superintendent Ian Krimmer said everyone working on the site had been accounted for.
The main concern now was the structural damage the fire could do to a large crane on the site.
The Western Distributor has been closed as a pre-caution, he said.
"If this crane was to come down it will be a concern," Superintendent Krimmer said.
3.14PM: Saffron Howden: As a result of the fire, the Western Distributor has been closed between the southern toll plaza and King Street in both directions, the Transport Management Centre said.
Southbound motorists are being diverted into York Street, while northbound motorists travelling towards the Harbour Bridge are being advised to exit the Western Distributor at Bathurst Street, or will be diverted at King Street.
Sussex Street and Hickson Road are both closed near the site of the fire and motorists are being advised to avoid the area.
Massive smoke plume erupts from Barangaroo as fire breaks out underground pic.twitter.com/gibbhbGrrs— Andrew Denney (@Andrew_Denney) March 12, 2014
3.09PM: Saffron Howden: There are concerns damage to a large crane - particularly its substructure - at the building site could cause it to topple, a NSW Fire and Rescue spokeswoman said.
As a result, nearby buildings had been evacuated and the southern approach to the Harbour Bridge had also been closed.
At at 3pm, there were 19 fire crews on site with three support crews. Among the crews were three HAZMAT teams.
The spokeswoman said the fire was in two levels of formwork underground in an area 50m by 50m.
3.07PM: Amanda Hoh: Ambulance NSW said people were being sent to evacuation points.
Two ambulance vehicles and three rapid response teams were on site at 3pm.
An ambulance NSW spokeswoman was unable to confirm if paramedics had treated any person for smoke inhalation or other injuries.
"We're still in the thick of it," she said.
3:03PM: KPMG management consultant Jaime Lee said her colleagues first noticed the smoke from their office window before they started smelling it inside the building.
The KPMG building is located next to Barangaroo and was evacuated about 2.45pm.
"'I was just walking past and everyone was lining up along the window and trying to figure out what was happening.
"Mostly the metal was on fire.
"I saw a lot of smoke then we could start smelling smoke in the building. It was a bit scary."
2:54PM: Fire and Rescue NSW Superintendent Ian Krimmer said all workers had been evacuated from the site and there were no injuries reported.
The area is being redeveloped as a residential and retail hub, with plans for a high-rollers’ casino owned by billionaire James Packer.
Witnesses report large plumes of smoke billowing from the site.
"There's about ten fire trucks, ambulances," said one witness, who was standing on the street near Hickson Road.
"It's right next to the KPMG building. It's like down underneath the ground in a pit.
"There's police and people everywhere, you can't see any flames and just a lot of smoke."
Office worker Danny Pezeshki said he could see heavy smoke from as far as his building on the corner of Park Street and George Street in the CBD.
Residents in Rozelle in Sydney's inner-west have reported spotting the smoke plume as well.
2:54PM: A fire has broken out in the basement of a building at Barangaroo in Sydney's CBD.
NSW Fire and Rescue were called at about 2pm on Wednesday.
At least six fire trucks have been deployed, with two already on the scene by 2:10pm, a New South Wales Fire and Rescue spokeswoman said.
''There are large volumes of smoke coming from the basement area in a building under construction at Barangaroo on Hickson Road,'' she said.
''They've called for more crews.''
The smoke could be seen right across the city skyline.