 That trauma then grows into negative feelings of isolation and self-loathing. Those feelings then build into suicidal ideologies, which can lead a disgruntled person to look into previous mass shootings and attackers. The final key to these series of warning signs is access to a gun. In terms of demographics, the Violence Project database finds that from 1996 through now, 97% of U.S. mass shooters are male. 81% of the K-12 school shooters have been white.