Police are hunting for the driver of a stolen van who was seen fleeing the scene of a train derailment at Kembla Grange on Wednesday morning.
Emergency services were called to the train line on West Dapto Road just after 4am to reports of a train and vehicle crash.
A four-carriage train travelling at high speed struck an unoccupied Nissan Patrol that was on the track, causing the front carriage of the train to roll onto its side.
Police said the car had been driven up to 50 metres onto the track from the level crossing, in what appeared to be a deliberate act.
Subsequent inquiries have revealed the vehicle was stolen earlier Wednesday morning from a home at Flinders and they're investigating how it came to be abandoned on the train line.
Witnesses have told police a male was seen running from the area soon after.
Eleven passengers and the train driver had to be assisted from the carriages, while the driver and three passengers were taken to hospital with minor injuries.
Officers from Lake Illawarra Police District established a crime scene and commenced an investigation early this morning.
Superintendent Craig Ireland said the northbound train was travelling at speed between Dapto and Kembla Grange when it hit the Nissan van on the tracks.
"Looking at the damage caused by the derailment it's a miracle someone wasn't killed or at least seriously injured," he said.
"... I was speaking to some of the railway workers on site and when they see a train in that position they immediately expect fatalities, so I think it's very fortunate no-one was hurt."
Superintendent Ireland said the car had been driven up to 50 metres onto the track from the level crossing, in what appeared to be a deliberate act.
"Part of the police investigation will be trying to establish exactly why that car, or how and why the car came to be left on the tracks," he said.
"A man was seen running from the scene just prior to the collision and he's certainly a focus of our investigation. We'd like that person to come forward if possible.
"... It doesn't appear to be a case of a simple breakdown and the fact someone's run from the scene prior to it indicates it's either deliberate or some sort of misadventure driving the car in that area."
NSW Ambulance Inspector NSW Ambulance Inspector Norm Rees said emergency services faced a chaotic, and dangerous, scene on arrival.
"The scene was chaotic, it was messy," he said.
"Someone had parked a van across the track and abandoned it; the train has hit it and as a result has derailed.
"Subsequently the first carriage has derailed and ended up on the siding, the second carriage has half tilted and the remaining two carriages remained on track.
"It had taken out all the infrastructure - the guard rails, the signals, there was debris all over the place.
"It had torn up part of the track and brought down power lines which were laying across the cabins and station platform - it was a dangerous scene."
Inspector Rees said the train driver was trapped for some time, prior to being released by NSW Ambulance and Fire and Rescue NSW personnel.
"The train driver, aged 39, was transported to hospital with minor abdominal and back pain, and two passengers were also taken to hospital with minor injuries," he said.
An Illawarra Shoalhaven Local Health District spokeswoman said four people had been treated at Wollongong Hospital for minor injuries - the 39-year-old man plus two other men, aged 64 and 48, and a 53-year-old woman.
By late afternoon all had been treated and released, except for the train driver who was admitted to hospital.
The Transport Management Centre has advised that buses are replacing trains between Wollongong and Albion Park on the South Coast Line due to the incident.
Trains will continue to operate between Albion Park and Kiama and between Wollongong and Waterfall.
Passengers may need to change at Wollongong or Albion Park to continue their journey.
Passengers are also advised to allow plenty of extra travel time, listen to announcements and check information displays for service updates.
Anyone who may have information, dashcam footage or CCTV is urged to contact Lake Illawarra Police Station on 4232 5599 or Crime Stoppers on 1800 333 000.
Read more Wollongong court and crime stories here.