CAMP SIONGCO, April 23 -- The leader of one of the three factions of the Moro militant groups allied with ISIS was killed along with his 11 followers in the military's air and ground assaults Monday in the Maguindanao del Sur town of Datu Saudi Ampatuan.

Among the fatalities are Mohiden Animbang alias Karialan, chairman of the Bangsamoro Islamic Freedom Fighters (BIFF)-Karialan Faction, and his brother, Saga Animbang, his operations chief, according to Maj. Gen. Alex Rillera, commander of the Army's 6th Infantry Division.

Rillera said the bodies of 12 slain extremists were recovered in a swampy area of Barangay Kitango with 12 assorted high-powered firearms following an hour-long clash.

"The battle site was an open swamp area, and fina...