Casualty Collection Points (CCPs) are NOT mandatory in an ac

Stimulus Drives the Movement

When asked, many officers believe that gunfire alone is the stimulus driving the push to “Stop the Killing” during an Active Shooter/Mass Casualty Incident. In reality, the operational stimulus is much broader and includes all fresh indicators of ongoing violence or imminent threat to life.

These stimuli may include:

• Screaming victims
• Rapid fleeing crowds
• Live 911 updates
• Strong smell of gunpowder
• Visual confirmation of the suspect
• New victims being shot or injured
• Immediate intelligence updates

The key is not simply the presence of gunfire — it is the presence of fresh, time-sensitive indicators that people are still actively dying.

Deliberate vs Exigent Movement in an Active Shooter 

 Mass Casualty Incident

One of the most important concepts for responding officers to understand is that movement should be driven by stimulus — not momentum.

Too often during Active Shooter / Mass Casualty Incidents (AS/MCI), officers continue moving aggressively through a structure long after the stimulus that justified rapid movement has disappeared. This creates unnecessary risk, contributes to “Blue Tsunami” chaos, delays medical rescue, and increases the likelihood of blue-on-blue incidents.

The question officers must constantly ask is:

“What stimulus is driving my speed, direction, and urgency?”

EXIGENT MOVEMENT

“Speed to stop active killing”

Exigent movement is appropriate when officers have fresh, immediate stimulus indicating ongoing violence or imminent threat to life.

Examples of Exigent Stimulus

• Fresh gunfire
• Screaming victims
• Rapid fleeing crowds
• Live 911 updates
• Strong smell of gunpowder
• Visual confirmation of the suspect
• New victims being shot
• Immediate intelligence updates

Characteristics

• Rapid movement
• Minimal delay
• Direct movement toward the threat
• Less methodical searching
• Immediate action focus

Purpose

The purpose is simple:

Stop the threat before more people die.

This is the “Stop the Killing” phase.

Officers accept greater tactical risk because every second of delay may mean additional casualties.

DELIBERATE MOVEMENT

“Control the unknown”

Deliberate movement begins when the stimulus decreases, becomes stale, or disappears entirely.

Examples:

• Silence
• No new victims
• Residual smell of gunpowder only
• Empty hallways
• Delayed or conflicting information
• Threat possibly contained or fled
• No active signs of violence

Characteristics

• Slower and coordinated
• Sector-based clearing
• Communication-heavy
• Methodical
• Focus on containment and control

Purpose

The purpose shifts from:

• stopping active killing

to:

• controlling uncertainty,
• preventing ambush,
• coordinating resources,
• and transitioning to rescue operations.

THE CRITICAL ERROR:

Continuing Exigent Movement Without Stimulus

One of the most common operational failures is officers continuing aggressive clearing operations after:

• the suspect is neutralized,
• barricaded,
• contained,
• or has fled.

This often happens because:

• adrenaline remains high,
• officers fear missing a second suspect,
• teams become momentum-driven,
• nobody establishes command transition.

The result:

• victims remain untreated,
• RTFs are delayed,
• evacuation corridors never form,
• officers chase “ghosts.”

THE OPERATIONAL TRANSITION

Stop the Killing → Stop the Dying

At some point, command must recognize:

The stimulus for exigent movement has changed.

Once the threat is:

• controlled,
• contained,
• isolated,
• or no longer actively killing,

the operational priority must transition rapidly toward:

• casualty rescue,
• corridor security,
• CCP establishment,
• evacuation,
• and integration of Fire/EMS.

THE KEY PRINCIPLE

Freshness of stimulus matters more than presence of stimulus.

A distant alarm does not equal active killing.

Residual gunpowder odor does not equal immediate threat.

Silence itself is information.

Officers must continuously evaluate:

• Is the threat still actively killing?
• Is there fresh stimulus?
• Or are we now operating in uncertainty?

PRACTICAL PATROL TAKEAWAY

Exigent Movement

• Fresh stimulus
• Immediate threat
• Speed prioritized
• Goal: stop killing

Deliberate Movement

• Reduced/stale stimulus
• Uncertain threat location
• Coordination prioritized
• Goal: control the environment and enable rescue