To deal with the complexities of decision-making for unmanned aerial vehicles (UAVs) in denial environments, this paper applies deep reinforcement learning algorithms to search and rescue (SAR) tasks. It proposes a two-stage target search and tracking method for UAVs based on deep reinforcement learning, which divides SAR tasks into search and tracking stages, and the controllers for each stage are trained based on the proposed deep deterministic policy gradient with three critic networks (DDPG-3C) algorithm. Simulation experiments are carried out to evaluate the performance of each stage in a two-dimensional rectangular SAR scenario, including search, tracking, and the integrated whole stage. The experimental results show that the proposed DDPG-3C model can effectively alleviate the overestimation problem, and hence results in a faster convergence and improved performance during both the search and tracking stages. Additionally, the two-stage target search and tracking method outperforms the traditional single-stage approach, leading to a more efficient and effective decision-making ability in SAR tasks.