( CNN ) -- Philippine President Gloria Macapagal-Arroyo lifted martial law in the country 's south , which she declared after the massacre of 57 people last month , Philippine news outlets reported Saturday . The order lifting martial law was due to be effective at 9 p.m. ( 8 a.m . ET ) Saturday , the Philippines News Agency ( PNA ) and CNN affiliate ABS-CBN said . Military troops will remain in Maguindanao province to keep the peace despite the move , said Victor Ibrado , chief of staff of the Philippine armed forces , PNA said . Arroyo imposed martial law December 4 but lifted it Saturday after deciding it had achieved its objectives , Executive Secretary Eduardo Ermita said , according to PNA . Local government was now back in power and the justice system was functioning again , he said . Authorities have said the November 23 massacre in Maguindanao province was a politically motivated attempt to keep an opponent of the politically powerful Ampatuan family from running for governor . Thirty journalists were among those killed . The martial law allowed arrests without warrants , and at least six members of the Ampatuan family -- including a local mayor -- were arrested , according to ABS-CBN . Authorities raided a warehouse and ranch belonging to the family last weekend and confiscated firearms , ammunition and vehicles , Maj. Randolph Cabangbang , deputy of operations for the eastern Mindanao command , told CNN . Ermita said Saturday that three charges of multiple murders were filed in court , and that 24 people were charged with rebellion . The Philippine National Police has referred nearly 900 other cases to the Department of Justice , he said . Violence in the run-up to elections is not uncommon in the Philippines . The Maguindanao massacre , however , is the worst politically motivated violence in recent Philippine history , according to state media . The victims included the wife and sister of political candidate Ismael `` Toto '' Mangudadatu , who had sent the women to file paperwork allowing him to run for governor of Maguindanao . He said he had received threats from allies of Gov . Andal Ampatuan Sr. , the father of the accused mayor , saying he would be kidnapped if he filed the papers himself . Maguindanao is part of an autonomous region in predominantly Muslim Mindanao , which was set up in the 1990s to quell armed uprisings by people seeking an independent Muslim homeland in the predominantly Christian Asian nation .
Reports : Order ##ed martial law was due to be effective at 8 p.m. ( 8 a.m . ET ) ET . Police have said the November 23 massacre in Maguindanao province was a politically motivated . At least three members of politically - powerful ruling family in the area were arrested . Maguindanao is part of an autonomous region in predominantly Muslim Mindanao .