These articles always bring out the guns vs. non-gun comments. The real problem is that we have a social learning and entertainment environment that subconsciously trains some of the young people that there is no consequence to their action outside of their personal sphere. The video games and Hollywood production for the most part reward the shooter with a state of euphoria. This is rewarding to a young person who is susceptible to illusions of grandure. This could explain the seemingly false " search and rescue " post and so forth, and lead to the texts and threats before action. 
Many folks this comment board talk about causes of death in for other activities. Are you aware that hospitals and medical practitioners probably kill more folks each year than anything previously mentioned. You can search and read for yourself, https://www.washingtonpost.com/news/to-your-health/wp/2016/05/03/researchers-medical-errors-now-third-leading-cause-of-death-in-united-states/