Spain has begun three days of mourning to commemorate the 68 people who died in a high-speed rail collision as hospitals continue to treat scores of injured passengers and rescuers scour the wreckage of the two trains for victims.

The trains – one from Spain’s state-owned Renfe and the other from the private rail company Iryo – were heading from Madrid on Wednesday to the southern region of Andalucía on the same line when they collided just before 9am. After the Iryo train came to a halt, the other slammed into its rear, knocking several carriages off the track near the town of Urda in the central region of Castilla-La Mancha.

Officials said on Wednesday another 107 people had needed medical treatment in hospital, including 15 who were in a serious condition.

The deadly crash came 10 months after 46 people were killed and dozens more injured after two trains – again, one from Renfe and one from Iryo – collided on the same line near the town of Adamuz in Andalucía.

The disaster has raised fresh questions…