>>511447364Ammonium nitrate is a principle component in bulk mining explosives, typically combined with diesel oil to produce the mixture known as ANFO (Ammonium Nitrate Fuel Oil). which is slurried into bore holes and used to remove geological layers in what you would call stripmining.
The Ammonium Nitrate readily gives up pure oxygen in response to heat or shock, making it an effective oxidizer to accelerate combustion of fuels. In this role it's known also as an accelerant.
Even lacking admixture with a fuel source, a large amount of ammonium nitrate exposed to heat or shock will result in rapid decomposition of the subtance, releasing excess oxygen, which will react with everything else nearby, so an explosion is still likely.
Some oxidizers can deflagrate and explode on their own, they are simply more efficient when mixed with a fuel due to the ratios of reaction products. I have never seen another example this extreme. Though I do remember a rocket propellant plant in Arizona detonated and killed a lot of personnel and firefighters some decades ago. They were producing ammonium perchlorate which is a more powerful oxidizer.