On the day of one of Europe’s biggest Christian festivals, an eight carriage high velocity train flew off its tracks killing at least 80 people.

In the city where it happened, Santiago De Compostela, Spain, the Christian festival fun came to a screeching halt and the city went into mourning.

Today, police paid a visit to the hospital to take the driver of the train into custody. The driver was under a formal investigation as the authorities tried to piece together the how exactly the derailment happened.

The investigation still continues.