06/08/2017 12:37 PM AEST | Updated 06/08/2017 2:11 PM AEST

Three Injured And Units Evacuated As Crane Collapses In Sydney

The cause of the collapse remains unknown.

Seven News
The crane collapsed into an apartment block in Sydney around 9.30am on Sunday.

Three people remain in a stable condition after a crane collapsed into the top units of a building in Sydney's south.

It is understood the crane toppled while being set up, crashing into the penthouse units of an apartment block on Brodie Sparks Drive in Wolli Creek, around 9.30am on Sunday.

New South Wales Ambulance Inspector Giles Buchanan said the three injured during the incident were treated on the scene before being transported to hospital.

"Three workers were treated and transported from the site with a variety of limb injuries, one appears to have a fractured leg," Buchanan said.

"There were five other workers who were assessed and didn't require further treatment."

Emergency services have evacuated a number of apartment blocks in the area following concerns the crane may shift.

Fire and Rescue NSW Superintendent Josh Turner said the majority of the damage to the building is sustained in the roof.

"The damage to the building of impact is in the roof area and in some of the air conditioning units on top," Turner said.

"Work is being done to assess the damage the crane has caused in the first instance and what work can be done to secure the crane -- our priority here is no further risks to persons on the site or surrounding the site."

7 News

Train lines between Central Station and Turrella on the T2 Airport line have been stopped due to the incident. Sydney Trains are urging passengers to allow extra travel time and double check train line closures.

No one was inside the crane when it collapsed.

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