Given the sheer number of mass shootings that have happened since the assault weapons ban ended in 2004, Americans are starting to notice when someone exhibits behaviors that could lead to committing an act of horrific violence.

According to FBI statistics, mass shooters exhibit an average of 4.7 examples of "concerning behavior" before their attacks. These include: mental health issues, interpersonal problems, suicidal ideation, discussing an attack, poor work performance, threats or confrontations.