Based on a wide range of sources, the author gives an analysis of the emergence, existence and relationship of two mass organizations of workers - the workers' police and the Red Guard. The structure of the armed groups of working class of Petrograd is for the first time investigated. The materials of the essays show the leading role of the Bolshevik party in the creation and activities of the Red Guard. The combat activities of the Petrograd Red Guard during the October Revolution and the first months of Soviet power are analyzed in detail.