At least 68 people were killed and dozens more injured on Wednesday morning when two high-speed trains collided in central Spain. The crash is among the worst in Europe's modern history and is Spain's deadliest rail disaster in 13 years.

The collision took place just after 09:00 local time (08:00 GMT), roughly 140km (100 miles) south of Madrid. A train traveling from Madrid to Seville ran into another train that was stationary on the tracks. The force of the impact sent several carriages down an embankment.

Transport Minister Óscar Puente said the stationary train, operated by private company Iryo and carrying 147 passengers, had stopped because of a computer failure. In such cases a 24-hour control centre in Madrid takes over. He said it made an "inexplicable" decision to tell the trains to move again with no speed restrictions. Iryo said its train was "struck from behind" by a service run by state-owned Renfe, which had 397 passengers on board.

Survivors described scenes of chaos. Salvador Arriza, 62, who was on the Renfe train, called the force of the crash "brutal" and told Reuters that passengers began smashing windows to escape. "Some people couldn't move because they were trapped amongst the seats," he said. One carriage caught fire, and images show a long section of railway track that pierced through another carriage.

Tangui Binier, 22, a passenger on the Iryo train, told the BBC that "suitcases started flying and people were screaming" as the train came to a stop. Outside, he saw the train "completely flipped over" and said his father carried a girl with a broken hip out of the wreckage. "I don't know if I'll ever recover," he said of what he witnessed.

Antonio Jiménez Barca, a journalist with El País, was heading to the Renfe train's cafeteria when the impact came. "I hit my head horribly.. I was covered in blood," he said. Another passenger, 46-year-old Sebastián Herrero, told El Mundo he felt he was "in the air for about four or five seconds" and saw "many people with broken noses, broken arms."

Dozens of ambulances went to the scene, and a helicopter evacuated the most seriously injured. Spain's Civil Guard said it would need DNA samples from relatives to identify some of the victims.

Prime Minister Pedro Sánchez visited the site and said: "The whole of Spain is grieving." He called it "unacceptable" for the country to suffer two serious train crashes in a single year and promised to "get to the bottom of this" and establish whether there was negligence. In January, a high-speed crash near Córdoba on the same rail line, though much further south, killed 46 people. The only deadlier recent accident was in 2013, when 80 people died near Santiago de Compostela.

Political reaction followed quickly. Opposition People's Party leader Alberto Núñez Feijóo said Spain "has the right to know what is happening with its infrastructure." The CSIF trade union demanded the transport minister resign, accusing him of "scapegoating" a traffic manager by blaming human error rather than "taking responsibility." Sánchez and other politicians cancelled public engagements on Wednesday, including campaigning for next month's parliamentary elections.