Abstract: A fire-retardant particle comprises a core formed of an aqueous solution and one or more inorganic compounds, which comprise ammonium phosphate. The particle further comprises a waterproof shell encasing the core. In an embodiment, a method of fighting a fire comprises encasing a hydrated fire-retardant compound in a waterproof shell of a fire-retardant particle. The fire-retardant particle is deployed in an area of fire. Moisture within the waterproof shell is heated by the fire. The waterproof shell ruptures as a result of the heated moisture so as to deploy the fire-retardant compound.