Oscar Puente told reporters in Madrid that the red signal was triggered by a computer communications failure, which automatically stopped traffic, and that an erroneous decision was then made to restart the Renfe train.

At least 68 people died when a Spanish high-speed express slammed into a stationary train on Wednesday, Spain's second fatal rail crash this year and Europe's deadliest since 2013, according to France 24. Sánchez said the tragedy will be investigated and that the country will strengthen high-speed rail safety if needed to rebuild confidence in the system.