In light of findings indicating that improved access to relevant information is crucial to reduce risk during emergency response, research has emphasized the need for decision support tools capable of aiding on-scene emergency personnel. Motivated by the latter, the aim of this thesis is to advance an understanding of how visualization can be used as a means to communicate risk information to operative leaders working in emergency situations. In particular, we identify the needs of operative leaders regarding access to- and communication of risk information; formulate requirements that solutions for visualization of risk should conform to in order to meet these needs; develop a solution for visualization of risk that satisfy these requirements; and evaluate this solution with respect to the previously identified needs. The identification of the needs of operative leaders is based on an empirical analysis and review of relevant research. The evaluation of the solution is based on an analytical walkthrough inspection with operative leaders, and comprehensive usability testing. The findings from the research indicate that operative leaders, in order to make sound decisions during emergency situations, often need to understand the underpinning cause of risk, and the location and nature of the physical objects posing risk. The findings also show that geospatial visualization is an efficient and effective means for generating such insight, enabling operative leaders to prioritize between risk objects related to an incident, and to rationalize why some risk objects are more critical than others.