As the sun rises over the wreckage near Cordoba, investigators are piecing together the timeline of Spain’s deadliest rail accident in decades. The collision between two high-speed trains has left 21 dead and a nation in shock.

Initial reports suggest a signaling failure may have caused the Iryo train to switch tracks into the path of the Renfe service. "It was a collision of immense force," said the Transport Minister. The incident has grounded parts of the high-speed network, stranding thousands and raising questions about the maintenance of Europe’s busiest rail lines.