Heavy machinery is aiding recovery after a deadly two-train crash in southern Spain, killing at least 41 people and injuring over 120. The accident occurred near Adamuz on Sunday evening when a Madrid-bound train derailed and hit an oncoming train. Rescuers worked through a second night hoping to find more survivors. Officials say most victims were in the front carriages of the Huelva-bound train. Spanish media report a 30cm gap or faulty weld in the rail may have caused the derailment. Transport Minister Óscar Puente called the crash "extremely strange" and said the death count "is not yet final." An investigation may take a month. Prime Minister Pedro Sanchez canceled plans to attend the Davos summit to focus on the disaster. King Felipe and Queen Letizia will visit the site on Tuesday. National mourning has been declared for three days. Renfe President Álvaro Fernández Heredia ruled out driver error, saying the trains were within speed limits and "the system itself corrects" human mistakes. Train drivers had warned in August about the poor state of the Madrid-Andalusia line and requested lower speed limits due to increased train weight and failures. Around 400 passengers and staff were onboard. Emergency services have 41 patients in hospital, with 12 in intensive care. Footage shows some train carriages tipped on their sides as rescuers pull people from windows and doors. The crash happened about an hour after the train left Málaga, pushing carriages of the opposite train into an embankment. High-speed rail services between Madrid and southern cities are suspended until Friday.