At a press conference on Wednesday afternoon, Spanish Transport Minister Óscar Puente said the collision had been caused by an official at the national railway control center in Madrid who “inexplicably” instructed one high-speed train to proceed along a track where another train had stalled.

Puente said the official who gave the order had been identified and was being questioned by Spain's Civil Guard and the country's Railway Accident Investigation Commission.

The minister stressed that Spain had “a safe transport system,” but added that “human action plays a role,” and that despite the plethora of safety regulations and protocols, “failures can occur.”

“We are absolutely devastated,” Puente said, expressing his “deepest sympathy and empathy” for the victims and their families. The minister, who has been touted as a possible future Socialist party leader, declined to answer a question about whether he would resign over the tragedy.

Earlier on Wednesday, Prime Minister Pedro Sánchez said he was “dismayed” by the accident and sent his “solidarity and support” to the victims and their families. He said emergency services were working at the scene to help those affected and ensure their safety.

Opposition leader Alberto Núñez Feijóo of the People’s Party said he was “very worried” about reports of a new rail accident and that the priority now was to help the victims and support their families.