Police said the fatalities Nestor Casabagan, a certain Celis and Alberto Maon were caught in the crossfire.
Casabagan was killed on the spot, while Celis and Maon died while being treated at the Cotabato Regional Medical Center here.
Witnesses said the victims were in front of a store in the town proper of Parang, not far away from the regional headquarters of the Autonomous Region in Muslim Mindanao police, when members of the Macapeges and Imam clans of Matanog town traded shots using military-type assault rifles.
The leader of the Imams, Matanog Mayor Hadji Nasser Imam, said he and his escorts were on their way to their town when PO1 Titing Macapages and his companions, positioned on one side of the road, opened fire, triggering the gunfight.
Macapages, however, said he was merely buying something from a roadside store when one of Imams escorts saw him and shot him with a rifle, prompting him to shoot back.
The Macapages and Imam clans, who have been locked in intense political rivalry, have figured in two previous clashes.
Senior Superintendent Akmad Mamalinta, ARMM police director, said he has sent emissaries to convince the elders of both clans to settle their differences amicably.