(CNN) -- A gunman killed three people and wounded at least five at the house of a mayoral candidate in the Philippines before polls opened on Monday, a military spokeswoman said. 

The attack happened around 2:30 a.m. (2:30 p.m. Sunday ET) when an unidentified gunman raided the house of a mayoral candidate in Zamboanga del Sur province, said spokeswoman Steffani Cacho. The incident is under investigation, she added. 

More than 50 million ballots have been printed with a dizzying number of candidates to choose from -- nine for president alone, among them front-runner Sen. Benigno Aquino III, son of a former president; and Joseph Estrada, a former president himself. 

Family dynasties also play a role: Former first lady Imelda Marcos is running to fill the Congressional seat of her son, Ferdinand "Bongbong," who is running for Senate, while her Congresswoman daughter Imee is running for governor. 

Boxing champion Manny Pacquiao also threw his hat in the ring: He's running for Congress too. 

In all. voters must fill some 17,000 other positions at the executive, legislative and local levels. 

A faulty test run of automated machines raised questions as late as Wednesday of whether the elections would even happen. A postponement would have stirred fears of a power vacuum on June 30 when President Gloria Macapagal-Arroyo is scheduled to end her nine years in office. 

Polls opened to crowds of waiting voters, CNN's Arwa Damon reported from Manila. 

"People are very excited," Damon said, adding that the election-day mood was "tinged with anxiety." 
What is he running for?
He's running for Congress too. 