ZAMBOANGA CITY: Philippine military choppers on Tuesday dropped thousands of feelers over a vast area in Maguindanao province urging armed followers of a powerful political clan — linked to the brutal murders of 57 people — to surrender peacefully.

“We have dropped feelers in the areas and urging armed followers of the Ampatuan clan to surrender peacefully,” said Colonel Jonathan Ponce, a spokesman for the Army’s 6th Infantry Division.

Security officials said thousands of troops and policemen were tracking down some 2,400 gunmen who are followers of the clan leader, Andal Ampatuan Sr., the governor of Maguindanao.

Also Tuesday, security forces raided the office of Ampatuan Sr. and seized more than a dozen automatic rifles, grenades and a machine gun and more than a thousand rounds of munitions.

“Military intelligence pinpointed the exact location of the arms cache and soldiers and police forces swooped down the area and recovered the illegal weapons. Civilian intelligence also helped us a lot in locating the weapons,” said Colonel Jonathan Ponce, a regional army spokesman. He said a militia commander Macapagal Camenden, believed to be the custodian of the weapons, managed to flee and is being hunted by security forces.

Ampatuan’s son Andal Ampatuan Jr., the mayor of Datu Unsay town, was said to have masterminded the mass murders. Among those killed were 30 journalists, and the wife and sisters, including supporters of a rival politician, Esmael Mangudadatu, the deputy mayor of Buluan town, who is a candidate for governor in Maguindanao.

President Gloria Macapagal Arroyo placed Maguindanao under martial rule on Dec. 4 and ordered the arrest of all those involved in the murders.

Police and military quickly arrested father and son along with Zaldy Ampatuan, the regional governor and his brothers Sajid Ampatuan and Anwar Ampatuan, the deputy governor of Maguindanao and Akmad Ampatuan, the mayor of Shariff Aguak and several clan members in connection with the mass murders, but they all denied the charges.