The invention relates to an apparatus, designed and configured for stunning live poultry animals which are intended for slaughter and are located in containers, by means of a gas mixture comprising a stunning gas, which apparatus comprises a stunning chamber having at least two stunning zones, an introduction station, arranged on the inlet side of the stunning chamber, for the or each container containing live poultry animals and a discharge station, arranged on the outlet side of the stunning chamber, for the or each container containing stunned poultry animals, at least one transport conveyor for transporting the or each container in the transport direction T through the stunning zones from the introduction station to the discharge station, as well as means for delivering the gas mixture into the stunning zones of the stunning chamber, which apparatus is characterised in that the means for delivering the gas mixture comprises at least one injection pipe which is designed and configured to be movable relative to the container for detachable connection to the or each container and for detachment therefrom, in such a manner that each container can be filled with the gas mixture when it is in the state of detachable connection to the or each injection pipe. The invention relates further to an arrangement comprising such an apparatus and at least one container, and to a corresponding method.