The driver and co-driver have been killed and several passengers injured when the Sydney to Melbourne XPT derailed in Victoria.
Emergency service workers said it was "a miracle" there were not more deaths among the 160 passengers.
The train left Central Station in Sydney at 7.40am on Thursday and was due to arrive at Southern Cross Station in Melbourne at 6.30pm.
It was running more than two hours late when it crashed around 7.50pm.
The diesel locomotive and five carriages derailed near Wallan station, 45km north of Melbourne, on the North East line about 7.45pm on Thursday.
Emergency services are at the scene and the rail lines between Melbourne and Sydney have been closed.
About 160 passengers were on board. It's understood that the two people who died were in the driver's carriage.
One person was taken to hospital in a stable condition and 11 others were hospitalised with minor injuries.
By 9pm on Thursday, CFA said the rescue had been completed.
At a triage centre set up at a nearby service station, a Sydney couple who had taken the train to visit their son in Melbourne said the tragedy had been terrifying.
"You just hang on for grim death. You're being thrown around, the things going along tilting over and all you can look out the window and just see dirt and debris and stuff flying up past the windows and the track itself is just twisted and bent," the man said.
"It probably went about 150 metres before it stopped, there were carriages going sideways - pretty horrifying."
The woman said her thoughts were with those who had died.
"We're very sad about that. Two people who went off to work this morning and never went home," she said.
The man revealed train staff had handed out complaint cards to passengers moments before the derailment, after lengthy delays caused by ongoing problems with signals on the line.
He walked back to the site of the initial derailment and said it appeared switches on the track appeared to have directed the train off the main line.
The train, which had left Central Station in Sydney at 7.40am, had been due to arrive at Southern Cross Station in Melbourne at 6.30pm.
It was running more than two hours late at the time of the crash.
The track buckled and both carriages shifted at least 10m from their normal trajectory.
The Australian Rail Track Corporation and Transport for NSW have been contacted for comment.
It is understood the ARTC is in charge of the rail maintenance, while the train was managed by Transport for NSW.
With Australian Associated Press