Unknown gunmen opened fire on the jeep and two motorcycles before dawn in the town of Rosario, just south of the capital Manila, said Chief Inspector Jonathan del Rosario.
The task force previously said 15 people had been killed in election-related incidents since the start of the year. But there are many other cases of violence that have yet to be fully linked to the elections.
Millions of Filipinos are expected to cast their votes on Monday to select new leaders ranging from president to town councillor.
Political violence is a recurring problem in the country, fueled by lax enforcement of laws and entrenched political “dynasties”, some of whom have their own private armies.