Ambush in Philippines kills 6 SUMISIP, Philippines, July 11 (UPI) -- Six rubber workers were killed Wednesday in an ambush as they were transported to a plantation in the southern Philippines, military officials said. Twenty-two others were wounded as a convoy of four trucks was sprayed with gunfire, Tempo reported. The victims were tappers, collecting the sap from the rubber trees, for the Tumahubong Agrarian Reform Beneficiaries Inc. Development Cooperative. The killings occurred on Basilan, an island that is a separate province. The gunmen were believed to be members of the Muslim militant group Abu Sayyaf, Tempo said.. The group has been blamed for killing the cooperative's workers in April in a similar incident, GMA News reported.