Three people were killed and one injured in a strafing incident near a polling center in Maguindanao province in the southern Philippines on Monday morning, the military said, Trend reports citing Xinhua.
The military said the attackers on board two vans opened fire at the peacekeepers assisting the voting process in Buluan town around 7:25 a.m. local time (2325 GMT).
According to the military, the victims were supporters of a local politician running for mayor in the town.
The Commission on Elections also reported another strafing incident on Monday morning in Sumisip town in Basilan province in the southern Philippines. The poll body said there were no casualties in the attack.
Earlier Monday, police reported at least eight persons were injured in grenade explosions in Maguindanao province on Sunday night, on the eve of the voting.
Police said the explosions hit Datu Unsay town, and another one hit nearby Shariff Aguak town.
No group has claimed responsibility for the explosions. Police are looking into the attacks in the areas tagged as "hot spots." Authorities said the eruption of violence in these areas did not disrupt the voting process.
Over 65.7 million Filipinos will vote on Monday to elect a new president, a new vice president, 12 senators, more than 300 members of the House of Representatives, and over 17,000 local officials.