At least four people were seriously hurt and another 45 left with minor injuries after a double-decker train slammed into buffers at the Alcalá de Henares railway station, Madrid, Spain, on December 22, according to official reports.

Transit company Renfe has launched an investigation into the cause of the accident and said the Cercanias train was traveling at ‘very low speeds’ when the accident occurred, and the driver tested negative for drugs and alcohol.

Alcala de Henares Mayor Javier Rodriguez was on the scene of the accident. Credit: Twitter/M.Rajoy via Storyful