But a spokeswoman for the national railway Renfe did not disclose the speed the train was traveling on an express track, where cars can go as fast as 250 kph. But she said the speed limit for the bend of track where the crash occurred is 80 kph.
Rafael Catala, secretary of state for transport and housing, told Spanish radio network Cadena SER that the "tragedy appears to be linked to the train going too fast" -- but that the reasons it was going so fast are not yet known.
The express passenger service was nearing the end of a six-hour trip from Madrid to the town of Ferrol, on the Atlantic coast, when the crash occurred, the state railway said.
Firefighter Miguel Angel Bello said the first four minutes after he arrived on the scene were a desperate race against time.
He and fellow firefighters smashed windows and kicked in doors to pull out the passengers trapped inside as rail cars went up in flames.
A young girl in the wreckage called out to him.
"She was under wreckage she said she wanted to get out and go home," he said. "But she died."
'It felt like a roller coaster'
Elder Stephen Ward of Utah was headed to the coastal Spanish town, ready to start a two-year Mormon religious mission.
The last thing he remembers from the train was flying sideways out of his seat.
"We had been going around some pretty sharp turns. We finally came to one more sharp turn, and the train, like, completely lifted up," he said. "It was leaning sideways. It felt like a roller coaster."
Ward, 18, blacked out when his car slammed on to its side, regaining consciousness only as he was being helped out of the train.
"I've got staples all over my scalp, I was covered in blood," he said. "They've scrubbed most of it off me now, but everyone was just covered in their own blood and occasionally the blood of others. It was gruesome to say the least."
Ward was discharged from the hospital Thursday, wearing a neck brace because of a cracked vertebra he suffered in the crash. Lacerations on his face are stapled shut, and there's a huge bruise on his leg.
Once he recovers, he plans to return to his missionary service.