UPDATE: At 1.30pm, one worker was freed and is being treated by NSW Ambulance.
At lease one person is still believed to be trapped - possibly two.
In breaking news, there has been an accident at a worksite in Macquarie Park.
Early reports suggest that a large pile of scaffolding, concrete and debris has fallen on top of two workers.
The workers are currently trapped underneath the rubble, with a delicate rescue operation underway.
More to come.