In this paper, we address the dynamic emergency medical service (EMS) systems. A dynamic location model is presented for locating and relocating a fleet of ambulances. The proposed model can control the movements and locations of ambulances in order to provide a better coverage of the demand points. The model can keep this ability under different fluctuation patterns that may happen during a given period of time. A number of numerical experiments have been carried out by using some real-world data sets. They have been collected through the French EMS system at the Hospital Henri Mondor, France. Finally, we present a comparison between the results of the introduced model and the outputs of a classical EMS dynamic location model. According to the observations, the introduced model provides a better coverage of the EMS demands.