It is believed the discovery of the woman's body is linked to the police incident currently at the scene, where a large crowd has gathered to watch.
One woman told news.com.au police had stopped her leaving the building.
She said her young children were alarmed to hear about the death of the young woman.
After the passer-by contacted emergency services early on Monday morning (local time), police and paramedics arrived on the scene.
The dead woman was thought to be aged in her 20s.
A NSW police spokeswoman said no other details, including the cause of death, were yet available.
The area is close to a number of apartment buildings and several businesses.
More to come.
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