The article describes the types of explosions, the conditions for their occurrence and the characteristics of their behavior. Based on the image of a mushroom cloud of explosion products that occurred at the optical-mechanical plant in Sergiev Posad, the approximate amount of the explosive involved in tritol equivalent was calculated, which amounted to 1750 kg. Based on this, an assessment of shock and explosive loads was carried out, and the degree of destruction of nearby buildings was determined. The calculated blast loads are described and compared with actual damage. An explosion of a similar mass of matter extended three times in time was assessed. For this case, the calculated loads are also given, which were compared with real damage. As a result of the calculations, it was concluded that, most likely, there was an explosion of the scattered substance. It was accompanied by a set of explosive phenomena moving from one combustion mode to another, as a result of which the duration of the explosive effect was increased by no less than three times. Thus, having information about emergency explosions, it is possible to reconstruct the scenario of the occurrence and development of an emergency situation, which is important when investigating similar incidents.