Instead, they are being redirected to a police command post.
Police are documenting children from a nearby childcare business as they are taken from the scene, a resident told AAP.
There are numerous exclusion zones around the structure as authorities work to establish if the building is safe.
Aerial footage by Seven Network shows fire crews setting up tents while police redirect traffic and pedestrians.
The website for the Opal Tower says the building has 392 apartments, commercial spaces, a childcare centre and community centre.
It cost $165 million to build.
Trains have been stopped as a result of the operation, the Transport Management Centre confirmed on Monday.
Australia Ave has also been closed in both directions and there are “significant local traffic impacts”, FRNSW said.
Fire and Rescue NSW is on the scene with specialist equipment designed to monitor the building for further movement.