Smoke grenades are single-use devices used by police to create clouds of toxic gas that obscure vision. This can be used to hide police movements, create a distraction or disorientate victims. Increasingly, police use smoke grenades containing hexachlorethane (also called HC, HCE or perchloroethane) as a “less lethal” weapon for crowd control. Chemicals produced by these grenades can cause severe injury or death.