Spain PM talks of "saddest day" during visit to crash site

The speaker, a resident of Santiago, expresses deep sorrow over a tragic event on the day of the apostle. He extends condolences on behalf of himself, the Spanish government, and citizens to the families and friends of the victims. Two investigations are underway: a judicial one and another by the Commission of Railway Accident Investigation under the Ministry of Development. The aim is to swiftly and accurately determine the causes of the severe railway accident.

¿Cómo describe el hablante el día del apóstol en relación a su vida personal?

¿Qué papel tiene la Comisión de Investigación de Accidentes Ferroviarios en este contexto?