An elderly woman and several others have been injured after a train hit a railway buffer at Richmond Station on Sydney's northwestern outskirts, with witnesses describing the scene as 'chaotic'.
More than a dozen people have been taken to hospital after a suburban Sydney train hit a railway buffer "at speed" at Richmond Station in the city's northwest.
Witnesses say passengers and crew were "sent flying" when the train crashed at the end of the line just before 10am on Monday.
A total of 16 people - including the driver and another staff member - were treated at the scene, NSW Ambulance said.
Fifteen were taken to various hospitals in the area for treatment, including a 21-year-old man with a suspected broken leg.
The remaining patients suffered less serious injuries - largely back and neck pain and cuts and bruising, NSW Ambulance's Paul Turner said in a statement.
"These people are very lucky," Supt Turner said.
"It was chaos. Things could've been much much worse."
Three choppers and dozens of ambulance and NSW Fire & Rescue teams raced to the scene following reports of several injuries.
Most of the injured were discharged from hospital by Monday evening, however, a number were still being treated.
Three women - aged 77, 69 and 60 - and a 22-year-old man remained in stable conditions at Westmead Hospital, while two men - aged 59 and 32 - were also stable at Nepean Hospital.
The impact caused some of the carriages to lift and dividers between carriages to crush, photos of the scene show.
Brett Saunders, who was on a platform at the station, said the train did not appear to brake.
"(It) crashed at full speed into the barrier sending everyone flying like superman! It was insane!" he wrote on Facebook.
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.
Jaiden Ruttley, who was towards the back of the train from Windsor, said people were screaming.
"We came to this sudden stop, it felt like the whole train had lifted up in the air," he told Fairfax Media.
Sydney Trains boss Howard Collins said it was too early to speculate on the cause but, from what he had seen, the buffer stop worked "effectively" and stopped the train from derailing.
"It is obviously very concerning," he told reporters in the city ahead of a scheduled meeting with unions over pay for train workers, which was postponed because of the incident.
NSW Premier Gladys Berejiklian assured Sydneysiders that authorities will find out what happened to make sure there is no repeat.
"I've not seen anything like this in my time and certainly our thoughts are with all the passengers," she told reporters.
"This is really concerning, fortunately, it's not something that happens every day and I don't for a second want to underscore how serious this incident is."
Transport Minister Andrew Constance said investigators from the Office of Transport Safety Investigators, the Office of National Rail Safety Regulator and Safe Work NSW will start work immediately.
"Safety is our number one priority and we will now work to determine what caused the incident," he said in a statement.
Investigators have reportedly begun retrieving data from the Waratah train's 'black box' recorder.