No worries. Ammonium Nitrate and Fuel Oil (ANFO) is the blasting agent of choice for mines and major construction material where you need to break up and move materials such as gravel or coal. A 50 pound bag of ANFO is extremely impressive although you need a high explosive to initiate it such as a cast booster that contains high explosive that is initiated by a blasting cap. This was obviously tons of material.
The danger with large quantities of fertilizer is if a fire generates enough heat while the material compresses itself so that an energized fire transitions to a detonation when the heat is unable to vent itself. You also have the concern of toxic fumes from such a fire or the ingredients. The tragedy list for fertilizer explosions is long and well known, but I am sure the firefighters in that town were aware of the danger they faced and how to approach such a fire.
The mayor said this was also a grain storage facility and he thinks the grain may have exploded, too. Rice and soybean and wheat dust is very combustible.