In mass casualty incidents, several members of Emergency Medical Services have to take actions in the field in order to cope with many injured or sick people. Incident commanders are responsible for managing operations, guiding rescue forces and applying resources appropriately under extraordinary circumstances. Data required for situation assessment, projection of developments and decision making are gathered by many different emergency physicians and paramedics. They are shared by numerous face-to-face talks, radio and phone calls as well as with the aid of paper-based forms and notepaper. While these tools and means of communication support flexible modes of operation, they often lead to deficient awareness of the situation. Due to temporal delays, poor handwriting and incomplete data, information sharing in the field is hampered, delayed and faulty. Compared to established paper-based artifacts, interactive cognitive artifacts might improve the situations by exchanging and visualizing data in real-time. However, because of users’ workload and working conditions, designing mobile computer-based tools and systems for this context of use is not only a technical but also a usability challenge. Based on the results of a two-year user-centered system design project in cooperation with German Emergency Medical Services, we discuss currently used and interactive cognitive artifacts for incident commanders. Challenges and approaches for successful user interface and interaction design are described and future work is outlined.