Police officers’ actions in which they have had to use firearms have significant implications, both professionally and personally, as well as an important social impact. The initiative of this study is to analyse real cases of firearm use during police interventions in armed confrontations, with serious life-threatening situations, to consider current training in this area and to propose future lines of action. The Institute for Public Security of Catalonia continuously looks to improve the various annual training sessions and, obviously, the training on the matter in hand. Thus, one of the aims of the Institute is to promote research into the various areas of safety, with the participation of experts and professionals from different disciplines to provide new knowledge and favour innovation in training. This study has been carried out over two years by a multidisciplinary group of professionals comprising members of the Catalan Government Police-Mossos d’Esquadra and specialists from the Ministry of Home Affairs and the Institute for Public Security of Catalonia, who have gathered the information and shared the results from different perspectives: those of training, legal and police intervention. For this purpose, they have used the individual testimony of police officers who have experienced situations of extreme use of force whilst performing their duties, who have explained their cases and made this work possible. For these reasons, and due to the importance of training in these cases, it has been deemed essential to disseminate the results of this study, particularly to shooting monitors and instructors and police procedure trainers, as they are commissioned with training our police officers. One of the first education activities was the Workshop organised at the Institute on 15 September 2016, in which three experts and authors of reference for this study took part and three Catalan Government Police-Mossos d’Esquadra police officers told of their experiences, representing all their colleagues who took part in the study. Another action is the publication of this work as the fourth edition in our “Safety Segments” collection, hoping it will be well received and a useful tool. I would like to thank the great ability and work of the authors of this study and, in particular, the invaluable participation of those who, voluntarily and generously, have passed on their experience with the conviction that it could help raise awareness among their colleagues, improve knowledge of these exceptional cases and, finally, have an impact on police training.