We develop and evaluate ASK-ASSIST, a decision support system that enables automatically setting up communication networks and sharing knowledge amongst security personnel, in particular when they are confronted with a series of unexpected incidents while on patrol. Currently, team leaders of mobile security guards are still forced to assess the consequences of a series of incidents and to take decisions in a heuristic way. On the basis of incomplete and uncertain information they have to determine the security situation, who to bring in contact with whom, and which personnel or which information systems should be lined up in order to resolve the incidents as a whole. ASK-ASSIST, however, automates robust dynamic formation and coordination of the right coalitions of security personnel, such that they support human improvisation in determining the nature of incidents and taking decisions by the coalitions. These coalitions comprise security personnel, communication security infrastructures and knowledge management security infrastructures. ASK-ASSIST is based on a framework for selforganization that generates ranked lists of incident-specific critical (re)configurations of coalitions in which joint tasks are assigned to agents associated with roles, like guards or team leaders. Our main contributions are the grounding and evaluation of the framework underlying ASK-ASSIST. We instantiate, validate and test the system on the basis of real data. These data concern organizational structures reflected in the coalitions and implicit or explicit feedback provided by personnel from a private security company. The provided feedback relates to the daily operational mobile security surveillance processes including those that involve functionalities of ASK-ASSIST.