 The commander of the planned action was Lwów Voivodeship's chief of police, Czesław Grabowski.Before the action commenced, around 130 Ukrainian activists, including a few dozen former Sejm (Polish parliament) deputies were arrested.The action itself began on 14 September 1930, in several villages of Lwów Voivodeship, where the cavalry unit of 14th Regiment of Jazłowiecki Ułans was directed, even though the detailed plan for the action was not established until 18 September.