Being dead certainly is an effective way to evade a manhunt for a while. Anyone dead-set on carrying out a shooting should try this step first for the ultimate cloaking.
But if you’re only considering murdering everyone around you and then yourself, maybe… you know… like, try talking to someone first. If that doesn’t work, try talking to a lot more people until the whole making-other-people-dead feeling goes away or becomes manageable.
Also, pills taste yummier than bullets. Try pills. Pills: brought to you by the people who would like to go home to their families tonight.