This paper presents the development of a controller for a fleet of Unmanned Arial Vehicles (UAVs) based on a distributed path planning strategy under a multi agent systems framework. The issue, treated as an online optimization problem, is solved using a Particle Swarm Optimization Algorithm (PSO). The proposal was validated in experiments, considering different scenarios like fixed and mobile targets, external disturbances, and the loss of an agent. The proposed PSO is implemented independently in each vehicle in order to determine, by minimizing a cost function, the best paths that ensure the fleet formation control, target tracking and collision avoidance