Manila, Philippines (CNN) -- The Philippine government declared a state of emergency in southern parts of the country Tuesday after gunmen kidnapped and killed more than 40 people, according to state-run media.
The military was deployed Tuesday in parts of Maguindanao to prevent more violence in the province, according to the Philippines News Agency.
On Monday, the kidnapped group -- which included the wife of gubernatorial candidate Ismael "Toto" Mangudadatu -- was abducted while on a trip to file his nomination papers for the May election. He had received threats that he would be kidnapped if he filed the papers himself.
The death toll from the massacre has fluctuated. The Philippines News Agency reported Tuesday afternoon that at least 37 people had been killed. Six minutes later, it reported that more than 40 had been killed.
The agency also said the government was placing survivors of the attack into witness protection.
Army officials said 100 gunmen surrounded the group of about 40 people -- many local journalists and women among them -- and ordered them out of their vehicles. They took the hostages to a mountainous region, officials said.
Some of the women were raped and tortured, according to media reports.
"Never in the history of journalism have the news media suffered such a heavy loss of life in one day," Reporters Without Borders said of the 12 journalists reported dead.
The military has said the gunmen are loyal to Maguindanao Gov. Andal Ampatuan, who has held control of the area for the past decade and is a longtime ally of President Gloria Macapagal-Arroyo.
Neither Ampatuan nor his advisers have commented on the allegation.
Maguindanao is a province in Mindanao, a Muslim autonomous region out of the control of the central government.
Jesus Dureza, an adviser to Macapagal-Arroyo, called the slayings "a gruesome massacre of civilians unequaled in recent history."
Elections in the Philippines have long been marred by violence, but Monday's abductions and killings shocked the nation.
Aid agencies operating in the region have long complained about a climate of fear in the region, where the government has little control and private armies operate freely.