MANILA, Oct. 5 (Xinhua) -- Six anti-drug agents were killed in an ambush on Friday in Kapai town in Lanao del Sur province in the southern Philippines, local police said.

Police said the victims, all agents of the Philippines' main anti-narcotics agency Philippine Drug Enforcement Agency or PDEA, were on board a car and were travelling to Marawi City when attacked by unidentified armed men around noon time on Friday.

The agents attended a program for drug surrenders in nearby Tagoloan town when ambushed, police said.

Police added that four of the victims died at the ambush site while two others died in a local hospital.