Recent advances in the Unmanned Aerial Vehicles (UAVs) sector have allowed these systems to carry multiple sensors, thus increasing their versatility and adaptability to a wide range of tasks and services. Furthermore, the agile performance of these vehicles allows them to adapt to rapidly changing environments making them an effective tool for emergencies. A single UAV, or a swarm working in collaboration, can be a handy tool for First Responders (FRs) during mission planning, mission monitoring, and the tracking of evolving risks. UAVs, with their onboard sensors, can, among other things, capture visual information of the disaster safely and quickly, and generate an up-to-date map of the area. This work presents an autonomous system for UAV-assisted mapping optimized for FRs, including the generation of routes for the UAVs to follow, data collection, data processing, and map generation.