This paper proposes a novel method to detect fire and/or flame by processing the video data generated by an ordinary camera monitoring a scene. In addition to ordinary motion and color clues, flame and fire flicker is detected by analyzing the video in wavelet domain. Periodic behavior in flame boundaries is detected by performing temporal wavelet transform. Color variations in fire is detected by computing the spatial wavelet transform of moving fire-colored regions. Other clues used in the fire detection algorithm include irregularity of the boundary of the fire colored region and the growth of such regions in time. All of the above clues are combined to reach a final decision.