A gas detection device and process detect a target gas for monitoring an area for the target gas. A radiation source emits electromagnetic radiation (50) that penetrates the area and impinges on an array of filters (15, 25) that distributes the impinging radiation (50) onto a first gas photosensor (35), a second gas photosensor (37) and a reference photosensor (36). The first gas photosensor (35) is only sensitive to radiation in a first wavelength range, the second gas photosensor (37) is only sensitive to radiation in a second wavelength range and the reference photosensor (36) is only sensitive to radiation in a reference wavelength range. The wavelength ranges are spaced apart from one another. An analysis unit (10) analyzes signals [Sig(35), Sig(36), Sig(37)] from the three photosensors (35, 36, 37) and carries out three pair comparisons to determine whether or not the target gas is present.