Austrian investigators last night overcame noxious fumes to enter the tunnel where 155 victims died in Saturday's fire and examined some of the badly burned bodies.
Investigators entered the first carriage of the train that was engulfed in flames shortly after beginning its ascent of the 3,200-metre Kitzsteinhorn mountain, 350 km west of Vienna.
The removal of the bodies from the tunnel, however, would be postponed until today, authorities said.
During the fire, temperatures in the tunnel reached up to 1,000 degrees, melting the train and burning the bodies of victims beyond recognition, according to investigators. Coroners will have to use DNA techniques to provide positive identification.
Only 12 people escaped from the train that was packed to capacity with skiers and snow boarders.
They were being treated in hospital yesterday.
One survivor of the blaze told yesterday of the "pure panic" among passengers as the carriage began to fill with smoke.
"They were trying to prise open the closed doors and smash the windows. My only thought was to get out, and I could save myself in the last second because a window was kicked in and I could fight my way outside," the unidentified survivor told the Austria Press Agency.
Among the victims were 52 Austrians, 42 Germans, eight from the US, 17 from Japan and 33 people whose nationality has yet to be confirmed.
At least 33 of the dead are believed to have been local government employees and their families who were on an office outing.
Many of the victims were teenagers on their way to a snowboarding competition.
"Only those who managed to save themselves survived. There was no chance yesterday of helping anyone," said Mr Franz Schausberger, governor of the state of Salzburg.
Investigators believe most of dead managed to escape from the carriage but were overcome by fumes in the tunnel as they fled.
The driver of a second empty train heading down the mountain also died in the fire.
Experts remained puzzled last night as to how fire broke out in the six-year-old carriage, which underwent its most recent regular safety check in September.
One theory is that the carriage may have already been on fire before it entered the three-kilometre steep, narrow tunnel.
"We have received information that the light of a fire was already visible to outside witnesses as the train was entering the tunnel," said Mr Erik Buxbaum, head of Austrian public security.
Police yesterday denied rumours that the train had no fire extinguishers on board.
"There were two fire extinguishers, one in the front and one in the back. It remains unclear if they had been used," said a police spokesman.
Over 30 counsellors began work round the clock yesterday helping survivors of the accident as well as families of the victims.
The Austrian Chancellor, Mr Wolfgang Schussel, visited the scene yesterday and attended an ecumenical ceremony in the nearby village of Kaprun with families of victims.
