The driver of a Spanish train that went off the rails at high speed, killing at least 80 passengers, is being held in custody in hospital as authorities investigate the cause of the country's worst such disaster in decades.
The driver's name and his location have not been given.
The investigation began on Thursday as state railway company Renfe said it was too early to determine the cause of Wednesday's crash, which also left 178 people injured.
Several media outlets said the train carrying 218 passengers and four crew members was going at twice the track speed.
One of the drivers who became trapped in the cab after the accident told railway officials by radio that the train had taken the bend at 190km/h, unidentified investigators told El Pais newspaper.
The speed limit on that section of track is 80km an hour.
El Pais' online edition quoted the driver as saying: "I hope no one died because it will weigh on my conscience."
A spokesman for the High Court in Galicia told the AFP news agency that a judge had asked that the driver be questioned to determine the cause of the crash.
Rocio Mosquera, the regional health minister, said some 95 injured passengers remained in hospital and gave warning that the death toll could rise further.
A video of the accident, outside Santiago de Compostela, showed the train on a curve as carriages in the middle of the train come off the rails and drag others with them.
Several witnesses spoke of a loud explosion at the time of the blast, but officials have ruled out terrorism as a cause of the accident.
"I was at home and I heard something like a clap of thunder. It was very loud and there was lots of smoke," said 62-year-old Maria Teresa Ramos, who lives near the site.
The train was travelling from the capital Madrid to the port town of Ferrol.
PM visits scene
On Thursday, smoke still billowed from the wreckage of mangled steel and smashed windows as bodies were laid out under blankets along the tracks.
Spain has opened two separate probes into the accident, the worst rail disaster in the country since 1944, when hundreds were killed in a train collision, also between Madrid and Galicia.
Mariano Rajoy, Spain's prime minister and a native of Santiago de Compostela, visited the scene and declared three days of mourning while King Juan Carlos and Crown Prince Felipe called off their public engagements.
"I want to express on the behalf of myself and the Spanish government my condolences to all the families of the people who have died, of which unfortunately there are too many," Rajoy said.
Renfe said the train had no technical problems and had just passed an inspection on the morning of the accident.