This paper presents the results of two compressed-natural-gas (CNG) -fueled busses in a burn test. The burn test was designed to mimic bus depot fire accidents. The rate of development of the fire from the engine compartment to the fuel tank area, time to fill the whole passenger compartment with smoke and the time to open the TPRD (temperature-triggered pressure relief device) were of interest in relation to the time for the fire brigade to arrive to establish a safety perimeter. The discharge of CNG and the evolution of the fire dynamics after opening the TPRD mounted on the fuel tanks were observed. The temperature on TPRDs as well as inside the bus were measured. Several cameras recorded the spread of fire and smoke both from outside and inside a bus. Measured data are crucial for safe and efficient rescue operations and the evaluation of threats imposed on the surrounding environment.