The lyrics for the first two verses is written from the perspective of a 15 year old school-shooter who calls himself “Johnny”, giving reasons why he is mad at the world.
The last verse instead is Johnny reflecting on his action after he is dead, bringing up the medias responsibility in encouraging other children taking after school-shooters.
Interestingly enough the song ends with Johnny being surprised everyone is looking at someone or something to blame, except for himself who committed the crime, in a similar fashion how he himself failed to take any responsibility for his own situation leading to his hate and anger.