Mass causality incidents generate a sequence of response events from the emergency services, requiring the allocation and use of resources in a timely fashion. In this paper we describe a system that helps emergency response services optimize their efficiency and coordination. The prototype we have developed provides an early assessment of the health condition of victims in mass casualty incidents, such as in a metro terrorist attack scenario. Our system utilizes information retrieved from passengers’ wearable or mobile devices for carrying out such an assessment. Additionally, we describe how we evaluated and optimized our system. Our main contribution is the enhancement of the existing emergency response process for mass causality incidents through the use of Pervasive Computing technology.