MANILA, Philippines - Security forces have uncovered another hiding place of ammunition allegedly owned by members of the Ampatuan clan in Shariff Aguak town in Maguindanao province, which has been placed under a state of martial law.

Police said its search teams discovered more ammunition from a warehouse allegedly owned by the Ampatuans in Barangay San Sebastian around 5 p.m. Tuesday.

It said search teams recovered 6,500 rounds of 7.62mm, 134 rounds of 81mm, 6 rounds of 90 mm, 131 round of 60mm, 3 pieces of 2.75mm rocket warheads and two round of 57mm.

Police said the ammunition was hidden in a cemented part of the warehouse. The ammunition was discovered based on intelligence reports, the police said.

Also on Tuesday, members of the Philippine Army's 37th Infantry Battalion were allegedly fired at by suspected members of a private armed group loyal to the Ampatuan clan during a search and recovery operation in Barangay Labolabo around 3:30 p.m..

Lt. Gen. Raymundo Ferrer, martial law administrator, said the troops were met by "bursts of automatic gunfire" by unidentified armed men.

Recovered from the village were one .50 caliber machine gun, a Garand rifle, a shotgun and several "blood-stained sacks," which have been turned over to the police's forensic experts.

The blood-stained sacks could have been used in the massacre of 57 people in Ampatuan town last November 23, which prompted the proclamation of martial law.

Ferrer said Monday that at least 900 firearms, small and high-powered firearms, have been recovered by security forces since the imposition of martial law in some part of the province last December 5.

He said security forces have also recovered millions of pieces of ammunition from several areas in Shariff Aguak, the main stronghold of the Ampatuan clan in the province.

Search teams have also found blood-stained police mobile units that were allegedly used in the massacre.

Several members of the clan, including its patriarch, former Maguindanao Gov. Andal Ampatuan Sr., have been arrested for alleged rebellion. The former governor is also being suspected of being involved in the November 23 massacre.

His son, Datu Unsay Mayor Andal Ampatuan Jr., is currently detained at the National Bureau of Investigation headquarters in Manila for allegedly leading the massacre, which left 26 females and at least 30 journalists dead.

Police said at total of 161 people, including policemen, local officials and paramilitary troops, were involved in the massacre. With a report from Noel Alamar, radio dzMM