Army and combat-trained police units also raided three mansions of the Ampatuan family in Davao City, east of clan-controlled Maguindanao province, on Sunday, said Major-General Gaudencio Pangilinan, military operations chief.
"We're not picking our targets at random," Pangilinan told reporters, adding troops were moving swiftly to neutralize the 4,000-member civilian militia force of the Ampatuans.
"These forces are not only a threat to the public safety and security of the province, they are also capable of committing terrorism, such as bombings, arson and attacks on our convoys," he said, adding authorities have disarmed only about 400 of the militia group.
Troops dug around the mango orchard owned by Maguindanao's former governor, a close ally of President Gloria Macapagal Arroyo and father of a local mayor who is the main suspect in the gruesome deaths of members of a rival political clan, lawyers, journalists, and civilians on November 23.
The killings -- the country's worst election-related crime -- raised fears next year's elections would be bloody and violent, but the tension is so far confined to some parts of Maguindanao, where Arroyo imposed martial law late on Friday to stymie reported rebellion plans of groups loyal to the Ampatuans.
The martial law order was officially announced on Saturday.
"We've been getting a lot of information from people who want to help us in our search for guns that may have been used in the murders," Colonel Leo Ferrer, brigade commander, told reporters.
Businesses and marketplaces were closed and streets were empty in Maguindanao province on Sunday, while civilians started to flee their homes and farms in fear violence may erupt soon.
"I advise you to stay put and be calm or go about your daily chores. Should our soldiers commit abuses, they will be relieved, investigated and punished," said Lieutenant General Raymundo Ferrer, Maguindanao military commander, who took over as governor. He said arrests and house searches would only be done on those suspected to be involved in the massacre.
Leaders of the two chambers of Congress agreed to convene the legislature as one body on Tuesday to debate on whether to support or revoke the imposition of martial law in the south. Arroyo's allies comprise an overwhelmingly majority of Congress.
Nearly 40 assault rifles, three machineguns and hundreds of crates of ammunition were dug on Sunday in tarpaulin-covered shallow pits at the farm near Shariff Aguak town on the southern island of Mindanao, Ferrer said.
Hours after the declaration of martial law, authorities found 330 boxes of bullets, three Armalite rifles, an armoured vehicle, two army vehicles and three police cars at a grains warehouse owned by the Ampatuans in another part of Shariff Aguak.
Andal Ampatuan Jr, now in custody, is suspected to have orchestrated the attack on members of a rival political clan on their way to file the candidacy of one of their leaders for elections next year. About 30 local journalists and two lawyers in the convoy were among the dead.


