Colonel Prudencio Asto identified the victims as Abubakar Mulod, 41, and Ekoken Kling, 15, both residents of Tonganon and alleged supporters of a certain Commander Teo of the Moro National Liberation Front.
Investigation showed that an unidentified perpetrator placed the grenade among a pile of sacks of corn grains owned by the victims Sunday night, Asto added.
The grenade exploded when the farmers lifted one of the sacks.
The victims were rushed to the Aleosan District Hospital in Aleosan, Cotabato for medical treatment, Asto said.
Investigators are checking leads that the grenade attack was related to a feud between Commander Teo and a certain Commander Karim of the Moro Islamic Liberation Front.