Up to 15 people have been injured in a train accident at Richmond station in Sydney's north-west.
Brett Saunders witnessed the crash just before 10am, which he described as "horrifying".
Fire and Rescue NSW were assisting the SES and multiple ambulance crews at the scene.
But Sydney Trains CEO Howard Collins reportedly said it was still on its rails.
Sydney Trains cancelled services between Richmond and Clarendon stations as a result of the incident.
A total of 17 ambulances crews and dozens of fire and police officers were called to the scene at Richmond station.
Paramedics who attended the scene treated some of the injured in a nearby park, police confirmed.
Officials said it is too soon to determine the cause of the crash.
Sixteen people were taken to hospital after a train hit the safety bollards in Richmond, sending people tumbling in the carriages.
Another 77-year-old woman also suffered a fractured clavicle and was being treated for spinal injuries as a precaution. "There was a huge amount of dust", he said.
The caller said the train came in at speed and hit the buffer and rebounded.
"We will provide more information as it comes to hand".
"Our main priority obviously given today is getting to the bottom of what has occurred here, and as I said, our thoughts are with those who were injured".
Transport Minister Andrew Constance described it as a "very serious incident" and investigations were underway by three separate regulators including National Rail Safety and the state's Office of Transport Safety Investigations.