A mass casualty incident (MCI) is any event that produces more patients than available resources can immediately handle. It could be a highway pile-up, a building collapse, an active shooter event, or a natural disaster. Whatever the cause, the principles of MCI management are the same — and knowing them before you arrive on scene can save lives.
Size Up the Scene Before You Commit Resources
The first arriving unit's most important job is not to start treating patients. It's to size up the scene and transmit a clear initial report. That report should include:
- Approximate number of patients
- Nature of injuries (trauma, medical, hazmat exposure)
- Scene safety status
- Resources needed
- Recommended staging location for incoming units
Committing all resources to the first patients you see can leave dozens of others without any care at all. Size up first.
Establish Command Immediately
The first arriving supervisor assumes command and holds it until formally relieved. Announce your command on the radio, establish a command post away from the immediate casualty area, and begin requesting additional resources based on your size-up.
Don't wait until you have a full picture to establish command. Announce it, start organizing, and refine your picture as information develops.
Implement START Triage
START (Simple Triage and Rapid Treatment) is the most widely used triage system for MCIs. It allows responders to quickly sort patients into four categories:
- Red (Immediate) — life-threatening injuries that can be treated with immediate intervention
- Yellow (Delayed) — serious injuries that are stable enough to wait for treatment
- Green (Minor) — walking wounded who can self-care or wait for transport
- Black (Expectant/Deceased) — injuries incompatible with survival given available resources, or confirmed deceased
Each patient assessment takes 30 seconds or less. Move through the casualty area quickly and tag patients. Don't stop to treat during initial triage — that comes after the sort is complete.
Establish Treatment Areas
Once initial triage is complete, establish separate treatment areas for Red, Yellow, and Green patients. Each area should be:
- Clearly marked and physically separated
- Staffed with medical personnel appropriate to the patient acuity
- Located away from scene hazards and media access
- Documented for patient tracking purposes
Treatment area supervisors report patient counts and status to the Medical Branch Director or Operations Section Chief.
Manage Patient Transport
Hospitals need to know what's coming. Establish early contact with receiving facilities to:
- Report estimated patient counts by category
- Distribute patients across multiple hospitals to avoid overwhelming a single facility
- Track which patients have been transported and where
- Coordinate air medical resources if needed
A transportation coordinator should manage all patient movement from scene to hospital to avoid duplication and gaps.
Document Everything
In the chaos of an MCI, documentation is easy to skip. Don't. Patient tracking, triage tags, transport logs, and resource records protect responders legally, support after-action review, and help families locate loved ones.
Assign a dedicated documentation function as soon as resources allow.
What This Means in the Field
MCI management is a perishable skill. The responders who perform well at real MCIs are the ones who have practiced these systems in drills and tabletop exercises — not the ones reading about it for the first time on scene.
Train now. Equip your team with the vests, guides, and tools that make command roles visible and coordination faster. At Response-Depot, that's exactly what we're here for.
Shop our MCI and incident command supplies and build your team's readiness today.
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