Tools and Resources to Help with Initial Detection

The following are tools for initial detection, including example tools and programs to help reporting, plus additional references to help identify warning signs of attack plots.

Tools for Increasing Tip Reporting



  • Tip Lines for School Safety: A National Portrait of Tip Line Use (Planty et al., 2020).
  • The Fortify Florida app is a statewide system to encourage reporting on school or other threats (FortifyFL, undated). Similar apps are available for Connecticut, Vermont, Virginia, Michigan, and some other states.
  • Safe2Say Something is an app for reporting on school threats in Pennsylvania; it is also available in other cities and states (Colorado and Utah) (Pennsylvania Office of the Attorney General, undated; Colorado School Safety Resource Center, undated; SafeUT, undated).

Social Media

Mental Health

Tools for Improving Identification of Observable Indicators


  • The Homegrown Violent Extremist Mobilization Indicators, 2019 edition, is a booklet providing details on 46 different behavioral indicators that may indicate a terrorist plot in progress (FBI, National Counterterrorism Center, and U.S. Department of Homeland Security, 2019). The booklet's focus is on jihadist terrorism, but most of the indicators are broadly applicable to most mass violence plots. For initial detection purposes, focus on the booklet's violence-related red and orange indicators; the yellow indicators are secondary risk factors, as described in the next section.
  • The FBI's Active Shooter Incidents: 20-Year Review, 2000–2019, provides indicators, warnings, and motivation information (FBI, 2021).


Integrating Detection Into Law Enforcement Actions

  • Use a Domestic Violence Interview Card, which requires asking about the presence of firearms in the home and access to firearms when responding to a domestic violence call to prevent potential use of guns in mass violence.
  • Wellness checks and in-person visits are important tools to use when someone is exhibiting a mental health crisis to assess their mental state, see whether weapons have been acquired, and identify warning signs.
  • Officers can be provided with a cheat sheet with indicators and behaviors.
  • Law enforcement without their own social media investigations unit can work with a neighboring agency's social media investigations unit or their local fusion center's social media unit.

Tools for Active Information-Sharing

Next Page in the Prevent Phase

Initial Detection - Recommendations