Reports claim that up to 12 people have been injured when a train failed to stop at Richmond station and hit the buffers.
Three people remain trapped.
Twenty ambulances and three rescue helicopters are currently at the scene.
Among the injured is a 70-year-old woman who has since been taken to Westmead Hospital for treatment.
A witness told 2GB radio station, 'There was a huge amount of dust. It's all chaos here.'
Sydney Trains CEO Howard Collins has said most passengers are suffering from 'cuts and bruises.'
NSW Transport has released a formal statement which can be seen below.
This is a developing story.