Spanish Prime Minister Pedro Sanchez has promised to get to the bottom of why two high-speed trains collided in southern Spain killing at least 40 people, as rescuers continue to search the wreckage.
After visiting the site of the crash, Sanchez also announced three days of national mourning for victims.
More than 120 more people were injured as carriages on a Madrid-bound train derailed and crossed over to the opposite tracks, colliding with an oncoming train in Adamuz on Sunday evening.
The crash is the worst the country has seen in more than a decade.
Rail network operator Adif reported that the collision happened at 19:45 local time (18:45 GMT) on Sunday, about an hour after one of the trains departed Málaga heading north to Madrid, when it derailed on a straight stretch of track near Córdoba.
The force of the crash pushed the carriages of the second train into an embankment, according to Transport Minister Óscar Puente, with most casualties occurring in the front carriages of the southbound train traveling from Madrid to Huelva.
Rescue teams reported that the twisted wreckage made it challenging to recover trapped individuals.
Sanchez expressed his sorrow, stating, This is a day of sorrow for all of Spain, for our entire country. He assured the public that the truth behind the tragedy would be uncovered with full transparency.
Puente indicated that an extensive investigation could take at least a month, calling the incident extremely strange. Initial investigations have pointed to a faulty joint on the rails as a potential issue, but it remains unclear if this fault contributed to the collision.
Four hundred passengers and staff were onboard the two trains, with emergency services treating 122 individuals; 41 remain in hospitals, including 12 in intensive care.
The type of train involved was a Freccia 1000, capable of reaching speeds of 400 km/h (250 mph).
King Felipe VI and Queen Letizia expressed their concern over the disaster, expressing heartfelt condolences to the victims and their families.
The Spanish Red Cross has mobilized to provide support and counseling at the crash site, addressing the anxiety of families awaiting news of their loved ones. With high-speed trains being key to Spain's extensive rail network, authorities have temporarily suspended services along affected routes.
