Some of the passengers were asleep, some had already started their working day on laptops - and others scrolled through their apps on their phones.

The journey was interrupted with an announcement that there was congestion on the tracks. This lasted a few minutes - for some, a bit longer for others.

Tangui Binier, 22, was in the Iryo train, the front carriage, number eight. His father was in number seven.

Their train was one of six to have been ordered to stop at 08:30. A few minutes later, "the train started speeding", Binier told the BBC, "then it came to a sudden halt".

Baffled, he looked out of the window and saw "wires on the left side come down, and then there being just a lot of smoke behind us."

Spanish journalist Roberto Gómez was dozing on the high-speed Renfe train which had stopped more than 25km (16 miles) away from Binier's.

It was a brief stop. A few minutes later, the train began to move again, he explained, and then the crash happened.

He did not know that at 08:36 his train had been ordered to proceed with the journey and some 17 minutes later the "truly unbelievable" happened, Spain's Transport Minister Óscar Puente said.

"The impact was terrible," Gómez told Onda Cero radio. "You can imagine, the carriage is completely destroyed. All the suitcases are all over the wrecked carriage."

Gómez suffered only minor injuries but described another passenger falling on top of him and sustaining a deep gash on his head.

"We were able to help people who had suffered severe blows to their chest and ribs," he said.

Rafael Barcelo was in one of the worst-affected carriages. A bruise on his forehead makes him one of the lucky survivors. He was having a coffee at the time of the crash and "felt a huge impact".

"We were all thrown into the air," he told Reuters news agency at the site of the crash.

"I am reasonably OK, my friend is quite worse."

"I was travelling in coach seven, which is the one with more victims and the one most destroyed. I at least counted eight victims in that coach," he said, visibly shocked.

Once the initial impact was over, passengers in Binier's carriage debated whether it was safe to leave because of the electrical wires strewn outside the train.

Some were worried about the risk of another train colliding and decided to exit.

"We did not know what had happened until we took a step outside, and there there was evidence of what had happened.

"We saw the other train behind ours and we saw our train completely flipped over and the back side full of debris," he told the BBC.

"When I got out of the train I was in complete shock, complete awe. There were people in danger, it was very hard to see, there was dead bodies, there was missing limbs. "

"I don't know if that is something I will ever recover from."

But the adrenaline kicked in, he said, and those like him who had not suffered any injuries went to help.

Among them was his dad, who he explained was "able to carry a girl to safety, with a broken hip".

It was not long before local people arrived, followed by the police and ambulance services of the Guardia Civil.

"I'm really one of the most fortunate people and the luckiest person. I feel like just I'm so fortunate and I see other people who are not so fortunate, and I see them very close up. Sometimes you just ask yourself 'Why me?'," he said.