The mass casualty emergency response involves logistic impediments like overflowing victims, paper triaging, extended victim wait time and transport. We propose a new system based on a location aware wireless sensor network (WSN) to overcome these impediments and assist the emergency responders (ER) in providing efficient emergency response during disasters like chemical explosions. In this paper we have only elaborated about the patient tracking and local air temperature monitoring functionalities of this system. We have developed an energy efficient ZigBee-ready temperature sensor node hardware and setup a ZigBee mesh network demonstrator. An RSSI-based localization solution is tested to analyze its suitability to track patients at the disaster site. A new algorithm to detect and display the temperature zones at the disaster site is developed and analyzed to find its computation efficiency. The patient tracking and temperature zone detection results show the increase of situation awareness, which can enable fast patient evacuation.