In September 1990, a referendum was held in the Krajina asking local voters if they agreed with Serb "sovereignty and autonomy" in Croatia, which was passed by a majority of 99.7%. The vote was declared illegal and invalid by the Croatian government. Babić's administration in Knin then announced the creation of a Serb Autonomous Region, named SAO Krajina, on 21 December 1990, and on 1 April 1991 it declared that it would secede from Croatia to join Serbia. Other Serb-dominated communities in eastern Croatia announced that they also would join the SAO.