Based on the Los Alfaques Disaster, a truck road accident which happened on 11 July 1978 near Tarragona, Spain and killed 217 people on a campsite.
Though the date of the disaster and many of the circumstances surrounding the accident were kept in the script, all the names were changed to not hurt sensibilities. For example, the camping's name was changed from the real "Los Alfaques" to "Las Arecales", and the company owner of the truck, "Enpetrol", to "SAG-GAS". All the personal stories, including the one of the truck driver and his son, are fictionalized ones too.