At least 36 people were killed when a newly introduced high-speed train came off the tracks between Turkey's main cities Istanbul and Ankara.
Many local people helped in the search for survivors
The government crisis centre initially put the death toll at 139 - but later revised the figures downwards without giving an official explanation.
Carriages overturned when the packed express derailed near the town of Pamukova, in north-west Turkey.
The cause of the crash was not immediately known.
There had been criticism of compromises made when the new train began running along the modified railway track last month.
But officials insist the train, carrying 230 people from Istanbul to the capital Ankara, was not travelling fast at the time.
There is a considerable military presence at the scene, which is now sealed off, the BBC's Jonny Dymond in Istanbul reports.
There were reports of chaotic scenes shortly after the accident happened at 1945 local time (1645GMT) in the province of Sakarya, around 100km (60 miles) east of Istanbul.
"The scene is one of carnage... There are people lying all over the place," journalist Oguz Dizer was quoted as telling NTV television.
At least four carriages overturned, and towns and villages in the area contributed medical and ambulance facilities to help the injured.
Local people were seen hammering on the windows of carriages to see if anyone inside was still alive.
Feridun Turan, mayor of the nearby town of Pamukova, told Turkey's NTV news channel: "We came to the site of the accident five minutes after it happened. People, parts of bodies were strewn all over the place."
Government officials initially reported that between 128 and 139 people had been killed - but they later revised the figure.
Prime Minister Recep Tayyip Erdogan - who cancelled a visit to Bosnia-Hercegovina to visit the scene - put the death toll at 36.
He said 68 people had been injured.
There was no official explanation for the early high estimate, but officials blamed confusion at the crash site.
"A mistake was made in the death and injury toll because
of the contradictory information that reached us,"
Ayhan Cevik, mayor of the nearby town of Bilecik, said.
Our correspondent says such incidents are rare in Turkey, where railways are not used as a major form of transport.