Multiple injuries have been reported following a train crash in Sydney's north west on Monday morning.
There are reports 15 people have been injured when a train hit the buffers at Richmond station and three people are trapped.
Seventeen ambulances and three rescue helicopters are at the scene. An elderly woman is among the injured in scenes that have been described as "chaotic".
NSW Ambulance received a call at 9.52am on Monday with reports of injuries, a spokesman told AAP.
NSW Ambulance said paramedics were treating 10 patients with minor injuries, and two with serious injuries.
Nine News has reported that the train failed to break, hit the buffers and obstacles at the end of the track and then lurched backwards leading passengers, who readying to disembark, to fall and injure themselves.
Media at the scene have reported passengers are "trapped" in the stricken train. Images have shown damage to carriages as they buckled together.
Two people have suspected spinal injuries, while another has a possible broken collarbone and another a broken leg, AAP reported.
A 70-year-old woman has been taken to Westmead Hospital for treatment and two others have been transported to Nepean.
One caller to Sydney's 2GB radio who saw the crash said there was an "almighty bang".
He said the train came in at speed and hit the buffer and rebounded. "There was a huge amount of dust," he said.
"It's all chaos here," another caller, Steve, told the station.
Richmond is a terminus station on the Sydney Trains network. On the rural fringe of the city, it is served by T1 Western line and T5 Cumberland line trains.
Media at the scene have reported passengers are "trapped" in the stricken train.
Sydney Trains CEO Howard Collins has left pay talks with union officials, aimed at averting a strike next week, to deal with the incident.
"I understand that the train on Platform 2 at Richmond has hit the buffers pretty hard," he told reporters.
"It is a Waratah train, it is one of our new trains, so we'll have a lot of good information about the train but it is too early to say (why the train overshot the buffers).
"My first thoughts are those people who have suffered some sort of injury. We don't believe any of those are life threatening or serious," he said.
"The 10:11am train service from Richmond to Central has been cancelled," Sydney Trains tweeted on Monday.
- More to come