GENERAL SANTOS City (Update) - A military official said Wednesday that the assault rifles unearthed at the back of the municipal hall of Ampatuan town in Maguindanao province could have been used in the massacre of 57 people last November 23.

"Considering the proximity of the area where the firearms were dug out, there's a possibility that the 16 firearms recovered at the back of the municipal hall of Ampatuan were used in the massacre," Lt. Col. Edgardo de Leon, commander of the Philipine Army's 73rd Infantry Battalion, told ABS-CBN News.

The firearms, which include 16 pieces of M-16 rifles, an M-14 rifle and an M203 grenade launcher, were unearthed from the back of the Ampatuan municipal hall late Monday afternoon.

Troops were fired at by unidentified men while unearthing the firearms, De Leon said.

The Armed Forces of the Philippines on Tuesday said five of the 16 firearms have been traced to 5 Civilian Volunteer Organization (CVO) members.

The paramilitary members have been identified as Brods Daulog, Madik Kamasa, Mastura Limba, Gador Limba and Rakman Sugadol.

The military on Wednesday morning brought the firearms to the Philippine National Police's regional headquarters in Camp Fermin Lira in General Santos City.

De Leon said the firearms will be subjected to ballistic examinations at the regional headquarters’ Crime Laboratory. He said the firearms and its bullets will be cross-matched with the slugs recovered from two grave sites in Ampatuan town.

The military commander said the site where the firearms were unearthed was only 5 kilometers away from the two grave sites.

Police and locals recovered a total of 57 people, mostly women and journalists, from the grave sites. A local journalist remains missing.

4 Ampatuans now in GenSan

Police, meanwhile, transferred three more Ampatuan clan members to the police camp in General Santos City.

Acting Maguindanao Gov. Sajid Ampatuan and his brother, Shariff Aguak Mayor Anwar Ampatuan and uncle, Maguindanao Vice-Gov. Akmad Ampatuan Sr. arrived at the police camp on board two Huey helicopters.

The three joined Autonomous Region in Muslim (ARMM) Mindanao Gov. Zaldy Ampatuan at the police camp.

Security forces arrested the 4 Ampatuans after martial law was imposed in Maguindanao province over the weekend.

The clan's patriarch, former Maguindanao Gov. Andal Ampatuan Sr., has also been arrested and currently detained in military camp in Davao City.

The Ampatuans are being accused of leading a rebellion against the government.

Other members of the clan are also being suspected of having involvement in the massacre, allegedly led by Datu Unsay town Mayor Andal Ampatuan Jr.

Ampatuan Jr. has been charged with 25 counts of murder and is currently detained at the National Bureau of Investigation headquarters in Manila. -- Report from Chat Ansagay, ABS-CBN General Santos