The article analyses modus operandi of perpetrators who carried out the bomb attack during the Boston Marathon on 15 April 2013. The author indicates the consequences of using this type of IED and explains how the location of the bombs affected the number of casualties. The article includes an analysis of the bombers’ tactics and the course of action beginning with the detonation of the bombs and ending with the apprehension of the last perpetrator. Moreover, the analysed attack shows something which does not receive enough attention – that terrorists make errors and act in a chaotic manner. A detailed analysis of the bombers’ preparation, behavior and modus operandi showed how poorly trained, insecure and chaotic the terrorists were. The slogan “Rely on Allah, not on your equipment”, popular in the jihadist media, has proved to be deceptive.