Renfe said the train came off the tracks on a bend about 3 or 4km (2-2.5 miles)
from Santiago de Compostela station at 20:41 local time (18:41 GMT) on
Wednesday.It was on the express route between the capital, Madrid, and the ship-building city of Ferrol on the Galician coast, with 218 passengers on board - in addition to an unknown number of crew members.
Firefighter Jaime Tizon, one of the first to reach the site of the crash, described the scene as "hell".
"I'm coming from hell, I couldn't tell you if the engine was on fire, or one of the carriages or what..." he told ABC after dragging the injured and bodies from the train.
Earlier, the leader of the regional government Alberto Nunez Feijoo described it as "a Dante-esque scene", in comments to Spanish radio.
One witness, Ricardo Montesco, described how the train carriages "piled on top of one another" after the train hit a curve.
"A lot of people were squashed on the bottom. We tried to squeeze out of the bottom of the wagons to get out and we realised the train was burning...I was in the second wagon and there was fire. I saw corpses," he told Spanish Cadena Ser radio station.
Several eyewitnesses described the train travelling very fast before it derailed. (BBC News)