This paper describes an approach for assessing potential casualties due to events that adversely impact critical infrastructure sectors. The approach employs the consequence calculation model (CMM) to integrate quantitative data and qualitative information in evaluating the socio-economic impacts of sector failures. This is important because a critical event that affects social and economic activities may also cause injuries and fatalities. Upon engaging a structured method for gathering information about potential casualties, the consequence calculation model may be applied to failure trees constructed using various approaches. The analysis of failure trees enables decision makers to implement effective strategies for reducing casualties due to critical events.