Uma isimo esiphuthumayo senzeke endaweni yomphakathi, isikhungo sokulawula sizonikeza isikhiye somnyango isignali yokuxhuma umlilo, futhi i-alamu yezwi efakwe kukhiye womnyango izokhipha i-alamu yezwi nomsindo we-siren othi “Lena indawo ephuthumayo, sicela uphume. ngokushesha”; Isibani esiyisixwayiso esinamathiselwe kusikhiya somnyango sikhipha ukukhanya kwe-laser ongakukhetha. Lapho abantu bephunyuka, inqobo nje uma bethinta noma iyiphi indawo ye-push rod yokukhiya umnyango, umnyango ungavuleka, futhi inani elikhulu labantu lingakhishwa ngokushesha okokuqala.