It is no secret; firemen face numerous dangers during interventions. Every fire is in itself an uncontrollable event and as such, highly unpredictable. Many factors affect the course of each fire, and it is thus extremely difficult to place all those factors into a single general model which would fully describe the behavior of a fire. When it comes to fires in closed spaces, the threats are multiplied because of the impossibility of energy exchange between the fire and its surroundings. Heat and smoke are not carried away in a sufficient amount which causes lower oxygen levels and gives way for dangerous toxins which can additionally combust. These conditions can cause a small fire to quickly escalate into a large fire. Events such as these have been the cause of many firefighters’ deaths around the world. To lower the risk of these events we first need to be well acquainted with the ways of emergence and behavior of the above-mentioned phenomena. Only then can that knowledge be used for producing higher quality personal safety equipment and better methods of training and extinguishing fires, which all lead to a safer and more effective fire extinguishing. Based on this view, the paper shows the basic elements of tactical approach to fire extinguishing in closed spaces and safety measures. In addition, this paper presents a simulation of indoor fire intervention and the paper proposes long-term measures that will make the work of intervention staff easier, more efficient and safer in such events.