The military showed its might Tuesday by flying bomber planes over a province under martial law, as helicopters dropped leaflets urging the surrender of a warlord's militia. The flights by the bomber planes in Maguindanao province were aimed at intimidating the 3,000 gunmen who are loyal to the Ampatuan clan accused of being behind last month's political massacre of 57 people. “We want to show to this group which does not want to be disarmed our capability if we decide to launch a tactical offensive against them,” Colonel Leo Ferrer, an army ground commander, told reporters. As the two OV-10 Bronco bomber planes flew over remote hilly areas where the militiamen are believed to have entrenched themselves, helicopter gunships dropped leaflets urging them to end their rebellion. The leaflets contained messages in the local dialect calling on the militiamen to “surrender for the sake of peace in Maguindanao”, Ferrer said in the provincial capital, Shariff Aguak. “There is also a telephone number to call if they wish to surrender. And the leaflets will serve as their safe conduct passes if they wish to do so.” This developed as government security forces unearthed late Monday afternoon another cache of weapons in Maguindanao believed to be hidden by militiamen who are loyal to the Ampatuans. The discovery came as government troops combed the province of hidden weapons and implemented Martial Law that the national government imposed in the province last Saturday. Reports sent to Camp Crame Tuesday said military and police search teams unearthed the latest weapon arsenal at the back of the Ampatuan Municipal Hall. Initial inventory of weapons unearthed includes 14 pieces of M16 rifles, an M16 with grenade launcher and an M14 rifle, the reports said. Security forces also arrested 19 people believed to be militia members loyal to the Ampatuans, the reports added. “The threat is still there,” military spokesman Lieutenant Colonel Romeo Brawner said in Manila. “Our troops are on high alert in the area against any further attacks. We are doubling our efforts.” The government allowed the Ampatuans and other clans to build up their own security forces to help overstretched military and police units on Mindanao. Rights group Amnesty International on Tuesday raised concern about the martial law arrests, but said it had not monitored any serious violations by troops.