Over the last several decades advancement in UAV technology has formed an important part of recent research. Nowadays, these flying robots are a great aid and even replace humans in many types of critical activities such as surveillance, fire protection, search & rescue (SAR), etc. In this paper, we study the design of SAR system using autonomous quadrotors UAVs. The developed system attempts to maximize the probability of target detection and minimize the expected search time while also minimizing the number of UAVs required. It is also adapted to counter UAV failures by re-configuring the UAVs to optimally continue the mission. Furthermore the SAR system algorithms are designed to accomplish the mission with a minimum amount of control information to be passed between UAVs. Finally a case study of survivor search and rescue operations is provided along with the obtained results which confirm the efficiency of the designed system.