Agrarian Reform Secretary Roberto Pagdanganan said the cases were filed against watchmen Freddie Mendadia, Ramil Ramos, Marcelino de la Cruz and Eduardo Talam, and agrarian reform beneficiaries Primitivo Caraballo, Ramon Desiduro and Henry Caspe, all members of the Workers Amalgamated Union of the Philippines.
Five of the suspects remain at large.
According to reports reaching the Department of Agrarian Reform, Mendadia and Ramos surrendered to the local police shortly after the fatal shooting of Diony Gaylan, 29, and wounding of Monserat Tayco, 63, and Angeles Gaylan, 53, who belong to another group of farmer-beneficiaries, the Nagasi Agrarian Reform Beneficiaries Multi-Purpose Cooperative (NARBMPC).
Philippine National Police chief Director General Hermogenes Ebdane has assured Pagdanganan the case will be pursued "vigorously until all the suspects are brought to justice."
The police and the military also gave assurances that they would maintain peace and order in the area.
The suspects allegedly shot Gaylan, Tayco and Angeles while the victims were cultivating Lot 799, a portion of the 1,004-hectare Hacienda Esperanza, previously owned by the heirs of the late Ambassador Roberto Benedicto and awarded to them under the Comprehensive Agrarian Reform Program.