DAVAO, Philippines, Oct. 11 (Xinhua) -- Suspected leftist rebels in southern Philippines killed four civilians and wounded another in an ambush, police said Sunday.

    The victims were heading to a chromite plant in the township ofImpasug-ong of Bukidnon province to work when they were ambushed by suspected New Peoples Army (NPA) members, police investigator Jun Efto said.

    The attackers fled after confirming the targets were dead, he said.

    Police has yet to determine the motive behind the ambush.

    The NPA, armed wing of the Communist Party of the Philippines, has been waging a guerrilla campaign in the countryside for four decades. Military estimates placed the NPA strength at more than 5,000 men scattered in more than 60 guerrilla fronts throughout the country.