Abstract: The routing in complex buildings is provided by information systems. But during a crisis situation, these systems may collapse due to certain incidents like an explosion, a fire or sabotage. The task of guiding people in this situation has to be handled in some way. In this paper we present a possible solution to this problem. We use a multi-agent system in a mobile ad-hoc network, without the need of any infrastructure. The main idea of the paper is that just by exploring the damaged building, the data of the changing environment becomes available and the challenge is how to fuse this data from different observers. We focused on the way of building, sharing and merging topological maps, using observations from individuals present in this infrastructure-less network. Besides a more efficient exploration of the building, the system presented in this paper can provide the rescue teams with additional services like finding the nearest exit. Some results of the tests we run with our system are also presented.