Abstract: This paper describes a concept for real-time positioning of first responders that includes a number of complementary sensors worn by the first responder, to increase accuracy and robustness in indoor and complex environments. By using sensors of different types, each with their own strengths and limitations, and fusing their respective outputs, the goal is to increase the usability of positioning information in time-critical and risky operations. This facilitates synchronization of activities and increases safety in the operation. The sensors included in the proposed real-time positioning module are shoe-mounted inertial measurement units, ultra-wideband radio, thermal and visual cameras, and GNSS. The fusion framework is based on factor graphs. This work-in-progress paper describes the individual sensor components and shows preliminary findings concerning the possibilities to improve position estimation through sensor fusion.