Just read another article that said this is the second explosion at that facility in 10 years.
Explosions are a hazard that exists in manufacturing and storage facilities of all sorts of explosives . . . military and civilian explosives, ordnance, ammunition, pyrotechnics/fireworks, etc. Very rare that such a facility will maintain a perfect record "forever." Some incidents are larger than others. The little ones, in which no one is killed, rarely make the news, except maybe very locally. When a large incident occurs, there are usually multiple casualties and much news coverage.
Safety protocols are serious and strictly enforced, and risks minimized and mitigated to the extent possible, but the nature of the materials involved means accidents will happen. Workers are advised of risks, trained, supervised, and periodically retrained.
Explosives and explosive items are obviously crucial for military use, but also critical to mining, demolition, building, fire fighting, law enforcement, scientific exploration, transportation, entertainment, etc.