MANILA, Philippines - Four voters were wounded when a home-made bomb went off Monday in a polling booth in La Union province just before the start of national elections, police said.
The bomb exploded in a corridor of the San Nicholas Academy in La Union province, just as people were lining up to vote, said police officer Amante Reyes.
The four victims suffered only minor injuries, Reyes said.
Despite the blast, the elections went ahead as scheduled in the school, which doubles as a voting center -- a standard practice in the Philippines.
In another incident in the southern city of Marawi on Monday, two bombs went off near school buildings, including one school being used as a voting center, said local military chief Lieutenant General Ben Dolorfino.
However the explosions in Marawi caused no damage or injuries, he said.
The type of bombs and the motive behind the incidents had yet to be determined, officials said.
Violence always plagues elections in the Philippines, with local politicians often using force to eliminate rivals' challenges or intimidate voters.
In other parts of the country at least six people were killed on Monday in shooting incidents involving supporters of politicians.