Philippine troops took the patriarch of a powerful clan _ a former governor _ and three other members of his family into custody Saturday after the president put his southern province under martial law to hunt down suspects in the country's worst political violence.
The head of the clan, Andal Ampatuan Sr., and at least six other family members who have ruled impoverished Maguindanao province unopposed for years are the main suspects in the Nov. 23 attack on a political rival's convoy in which 57 people, including 30 journalists, were killed. The family has denied involvement.
President Gloria Macapagal Arroyo on Saturday put Maguindanao under martial law, allowing troops to make arrests without court warrants and restore order, her top Cabinet member, Executive Secretary Eduardo Ermita, announced.
It was the first time that martial law has been declared in the country since the late dictator Ferdinand Marcos imposed it nationwide in 1972, paving the way for his one-man rule that ended with his ouster in 1986.
Under the post-Marcos constitution, Arroyo can enforce martial law for 60 days, unless Congress revokes or extends it.
Soldiers seized a large cache of weapons and ammunition that was buried near one of the Ampatuans' homes in Shariff Aguak, the provincial capital. Raids on four residential compounds yielded only one shotgun, a few bullets and empty ammunition boxes.
Armed forces chief Gen. Victor Ibrado said Ampatuan Sr., a three-term provincial governor, and his son Zaldy, governor of the Autonomous Region in Muslim Mindanao, which includes Maguindanao, were taken into military custody early Saturday. Two other sons and five other men sought in connection with the massacre were also detained, police said.
Another son, Andal Jr., turned himself in last week and was charged with multiple counts of murder.
The patriarch was taken later Saturday to a hospital in southern Davao city due to hypertension, local military spokesman Maj. Randolph Cabangbang said. The hospital was surrounded by soldiers and police.
Reading the martial law proclamation on national television early Saturday, Ermita cited military reports as saying heavily armed supporters of the Ampatuans had "plans to undertake hostile action" if clan members were arrested.
"We felt that this is a very imminent threat, so we recommended this proclamation," Ibrado said. "By their sheer number, they are really a threat to the peace and order of the province."
For several days, hundreds of security forces have surrounded the sprawling Ampatuan compounds in Shariff Aguak to prevent the clan from escaping. They dug out an entire arsenal including mortar shells, light machine guns, assault rifles and bazookas buried near the patriarch's mansion, said armed forces spokesman Lt. Col. Romeo Brawner.
Some of the weapons and ammunition were marked as belonging to the national police and the Department of National Defense. Three armored personnel carriers also were seized, Brawner said.
Arroyo has ordered an investigation of police and soldiers who may have supplied the weapons and ammunition, national police Chief Jesus Verzosa said.
Arroyo also ordered the creation of an independent commission to oversee the dismantling of clan-dominated private armies in the country and investigate the carnage, Interior Secretary Ronaldo Puno said.
The 57 people killed in the massacre included the wife, sisters and supporters of Esmael Mangudadatu, who had sent them to submit his candidacy papers for governor, challenging the Ampatuan clan's iron-fisted control of the province.
Thirty journalists and their staff _ the highest number of reporters slain in a single attack anywhere in the world _ were also killed. Eight of the journalists were buried in a common grave Friday after a funeral procession in which their coffins were carried on a flatbed truck bedecked with flowers and a banner reading "We want justice." Residents threw more flowers as the procession passed.
The Ampatuan clan, notorious for running a large private army purportedly for protection against Muslim separatist rebels, has been allied with President Arroyo, who received crucial votes from the region during 2004 elections.
Arroyo has promised swift justice in the killings and her ruling party has since expelled the Ampatuans.
Associated Press writers Oliver Teves and Teresa Cerojano in Manila contributed to this report.