Mass casualty incidents are a challenging safety-critical domain with high complexity, where management and decision-making can make the difference between life and death. As current paper-based tools and software solutions have severe limitations, we examine the use of integrated computer-based support systems in this domain. Instead of being primarily focused on the replacement of paper-based tools, we are looking for additional value of computer systems to support the incident commanders by providing appropriate presentations and offering assistance functions with different automation approaches. For this purpose, we are developing modular software components that can be combined to an integrated system for the management of casualties. We use a user-centered design approach. Therefore, the needs and abilities of prospective users were analyzed thoroughly and considered in system design. This includes interviews and field observations as well as formative evaluations of prototypes. This article summarizes our research for such an integrated management system for MCIs.