A major medical incident is defined as an incident involving more than how many patients?

• A. More than 25 patients
• B. More than 3 patients
• C. More than 10 patients
• D. More than 1 patient

Answer: (B)

In EMS, incidents are scaled by how many patients require care and how much resource effort is needed. When the number of patients rises beyond what a typical single-unit response can handle with standard resources, the situation is treated as a major incident, triggering organized incident management and triage. The threshold here is four or more patients—that is, more than three patients. Once you reach that point, teams usually activate an incident command system, request mutual aid, establish staging, and begin triage to prioritize care and transport.

If there are only one to three patients, the response generally stays within routine operations and doesn’t require the full major incident protocols. So the idea to remember is four or more patients means a major incident.