A passenger on the Spanish train, which crashed killing 80 people, has been describing the moment it flipped off the track.
Robert Fariza from Houston in the U.S. says he believes the train was going very fast into the bend.
Early investigations suggest it was traveling at more than twice the 50mph speed limit.
The driver of the train is to be questioned by police in hospital where he has been placed under surveillance.
178 people were injured in the crash 94 of them remain in hospital. 32 are described as critical including 4 children.
Two probes are underway to determine the cause of the tragedy.
Mr Fariza was with his wife who was seriously injured: