Firefighters walk past the locomotive as they work at the site where at least one person died and five were seriously injured when a regional service train collided with a collapsed wall between Sant Sadurni d'Anoia and Gelida, near Barcelona. AFP
Here is what we know about the country's deadliest rail accident in more than a decade.
What happened?
On Sunday at around 7:45 pm (1845 GMT), the last three carriages of a Madrid-bound service operated by rail firm Iryo derailed, crossing onto the oncoming track and colliding violently with a train travelling in the opposite direction run by state company Renfe.
Both trains were moving at more than 200 kilometres (124 miles) per hour and together were transporting more than 500 passengers.
Have all the victims been found?
The final death toll remains unconfirmed. Rescue teams continue to work at the accident site near the village of Adamuz to recover bodies.
Forty-three bodies have been found, with 41 of them identified through DNA testing.
Forty-five people have been reported missing, suggesting that some victims may not yet have been located.
Where does the investigation stand?
The causes of the accident remain unclear. Authorities are examining a crack in a section of track, though it is not yet known whether it caused or resulted from the derailment.
Transport Minister Oscar Puente said Wednesday that "two or three" trains that passed just before the Iryo train had "notches" that may have been caused by the track break.
Trains that passed an hour before the Iryo did not have such marks, he said.
The undercarriage of a train found half-submerged in a stream near the crash site could shed light on the cause of the derailment that led to the collision.
Interior Minister Fernando Grande-Marlaska said Tuesday that the investigation was considering all hypotheses but had ruled out sabotage, saying this "was never considered".
"From the beginning, we have been talking about technical issues related to railway transport. There has never been any element suggesting otherwise," he said.
Calls to the control centre
Daily newspaper El Pais on Wednesday published recordings of telephone conversations between the control centre at Madrid's Atocha station and the trains, revealing chilling exchanges.
"I have blood on my head," said the conductor of the Renfe train, which was hardest hit and where most of the bodies were located.
"I don't know if I can reach the driver. I'll go look for him," she said confusedly, while the person at the Atocha control centre asked about the train's condition.
The driver of that train died.
Another recording shows that the driver of the other train was unaware of the severity of the impact.
"Hello, Atocha, look, I just had a collision near Adamuz," he said, while the sound of emergency braking can be heard in the background.
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