Both inhibiting (reducing) and activating (oxidizing) reaction-diffusion waves were observed in a shallow liquid layer of the Belousov-Zhabotinsky reaction under the exclusion of oxygen. The wave velocity of the rarely observed reducing waves is lower than the velocity of the oxidizing waves. It increases with increasing malonic acid concentration and depends only slightly on the concentration of the other reaction components, in contrast to the dependence of oxidizing waves. Growing and shrinking ring patterns resulting from the interaction of both types of waves were observed for the first time and are described by spectrophotometrically determined space-time portraits. The reducing wave is classified as a trigger wave of Br ions. An a priori estimate of its velocity is in agreement with the currently estimated rate of Br generation. The possible connection to spatiotemporal patterns of morphogenes is pointed out.