A mass casualty incident is defined as a large number of victims overwhelm the community's ability to respond with existing resources; requires outside resources.

• A. An extraordinary event that can be managed with existing resources
• B. A large number of victims overwhelm the community's ability to respond with existing resources; requires outside resources
• C. A routine incident with minimal impact
• D. An incident that does not require outside assistance

Answer: (B)

A mass casualty incident is about surge capacity: when a large number of victims overwhelms the community’s ability to respond with existing resources, requiring outside resources. This definition emphasizes the mismatch between demand and available capacity and the need for mutual aid and external support to manage the situation.

Think of it as a situation that goes beyond normal response capabilities. If it could be handled with the resources already on hand, it wouldn’t be labeled an MCI. A routine incident with minimal impact doesn’t stress systems or require outside help, so it isn’t an MCI. An incident that doesn’t require outside assistance contradicts the essential element of overwhelm and the need for additional resources.