Spain is in shock after a high-speed train collision in Toledo province on Wednesday morning, October 28, left at least 46 people dead and 179 injured. Reports say a Renfe AVE bound for Seville rear-ended a stationary Iryo train near Urda, between Los Yébenes and the town of Urda, at about 8:54 a.m. local time. Several carriages derailed in the impact, and some tumbled down an embankment, which made the rescue work even harder. Around 544 passengers were on the two trains, and emergency crews worked through the wreckage to reach people who were trapped.

Why a train was sitting on the track, and why a second one was allowed to run into it, are now the big questions facing investigators. Early reports point to a possible signal or control issue, but the cause has not been confirmed, and the death toll is still being treated as preliminary. Spain has also suspended high-speed rail traffic between Madrid and Andalusia while the scene is examined. The crash comes just nine months after the Adamuz disaster in January, when an Iryo train derailed into an oncoming Renfe train and 46 people were killed. Two catastrophes on the country's high-speed network in a single year are bound to raise hard questions about rail safety.