The perpetrators of the Toranomon Incident and the Sakuradamon Incident were caught red-handed, while the Kotoku Incident and the Bokuretsu Incident were uncovered in the plotting phase.
虎ノ門事件と桜田門事件が現行犯で、幸徳事件と朴烈事件は、当時、計画段階で発覚したとされた。