Supporters of presidential candidate Ferdinand Marcos Jr. are seen during his final campaign rally for the 2022 national and local elections in Paranaque City, the Philippines, May 7, 2022.Photo:Xinhua

Three security guards were killed Monday when gunmen opened fire at a polling station in a restive region of the southern Philippines, police said, as millions of Filipinos voted in national elections. 

The deadly shooting happened shortly after voting got under way in Buluan municipality on Mindanao island.

Former mayor Ibrahim Mangudadatu told AFP that people inside the school being used as a polling station ran for cover when the shooting started. 

A fourth guard was wounded in the attack, said Maguindanao provincial police spokesperson Major Roldan Kuntong. 

It came after five grenades exploded outside a polling station in Datu Unsay municipality late Sunday that left nine people wounded.

Minutes after that attack, a grenade exploded in the neighboring municipality of Shariff Aguak, but there were no casualties. 

Both of those towns are also in Maguindanao province.

Police said the grenade victims had walked from their remote mountain villages to cast their votes at the municipal hall in Datu Unsay when polling stations opened across the country on Monday morning.

"It is their custom to come down early from their villages, which are located eight to 12 hours away on foot," said Kuntong. 

In 2009, Maguindanao was the scene of the country's deadliest single incident of political violence on record.

Fifty-eight people were massacred as gunmen allegedly working for a local warlord attacked a group of people to stop a rival from filing his election candidacy.

Dozens of the victims were journalists covering the contest.

AFP