It has been strongly recognized that increasing use of information technology (IT) in business operations has increased the risk of cascading failures in interdependent critical infrastructures (CIs). Dependencies are primarily due to services and resources that CIs must provide one another to maintain vital functions of the society. From a crisis management perspective, magnitudes of such interrelationships strongly rely on specific nature of disruptive events. This paper adopts a system dynamics modelling approach for simulation and analysis of disruption scenarios. We seek to characterize CI disruptions according to relevant aspects of risk assessment and response coordination as well as environmental, human, economic and other impact factors. Results are key to the design of a cyber incident early warning system for CI operators.