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Learn to recognize armed intruder pre-attack behaviors

Being alert and watchful can go a long way toward protecting your people and organization. Keep in mind, it is impossible to predict violent behavior and there is no single profile or warning sign that can reliably identify a person who is planning an attack. However, it may be possible to prevent some attacks through effective threat assessment and management strategies. 

By studying the pre-attack behaviors of active shooters in the United States between 2000-2013, the FBI produced a reference guide to help identify the warning signs. 


In the FBI study sample, the 63 active shooters were not readily identifiable by demographics. 

  • The vast majority (94%) were male. 

  • 57% were single (relationship status) at the time of the attack. 

  • About one-third had an adult criminal record. 

  • Nearly two-thirds had a history of abusive behavior. 

Planning and preparation 

Of those active shooters included in the FBI study, 73% had a known connection to the site of the attack. In cases where the amount of time spent planning and preparing for the attack could be determined, 46% spent a week or longer. 


According to the FBI study, active shooters experienced multiple stressors in the year prior to the attack. The top stressors reported included: 

  • Mental health (62%). 

  • Financial strain (49%). 

  • Job-related stressors (35%). 

  • Conflict with friends/peers (29%). 

  • Marital problems (27%). 

  • Abuse of drugs/alcohol (22%). 

Of the active shooters in the FBI study, 25% had a diagnosis of mental illness prior to the incident.  

Concerning behaviors 

Most active shooters in the FBI study displayed multiple concerning behaviors observed by others. The most frequent included: 

  • Behaviors connected to mental health issues (62%). 

  • Interpersonal interactions (57%). 

  • Leaking information (56%). 

  • Quality of thinking or communication (54%). 

  • Work performance (46%). 

  • Threats/confrontations (35%). 

  • Anger (33%). 

  • Physical aggressiveness (33%). 

Concerning communications 

More than half of the active shooters in the FBI study who had a specific target made threats or had a prior confrontation. Those threats and confrontations were almost always (95% of the time) in person, and rarely in writing or electronically. Although none of these observances were reported to law enforcement, 51% leaked an intent to commit violence. 

Primary grievance 

In the FBI study, most active shooters seemed to be acting on a grievance of some kind. Even those with no identifiable grievance demonstrated at least two concerning behaviors that were observed by others. The most common grievances were: 

  • Adverse interpersonal action (33%). 

  • Adverse employment action (18%). 

  • Other, e.g., general hatred of others (10%). 

Of 50 active shooters in the study with an identifiable grievance, nearly half of them experienced a triggering event. 


The seemingly random nature of active shooter events is what makes them especially terrifying. In the FBI study, only one-third of the active shooters victimized only random members of the public, while two-thirds arrived at the site of the attack with a specific person or persons in mind. 

If you suspect someone may be planning a violent attack, you should immediately report your suspicions to law enforcement or a threat assessment team. 

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