Moro Islamic Liberation Front (MILF) rebels ambushed and killed four rubber plantation workers and a militiaman while eight others were wounded Sunday morning in the hinterland of the southern province of Basilan, officials said. Basilan Vice Gov. Al-Rasheed Sakalahul, citing police reports, said the victims were bound to a rubber plantation when they were attacked by 40 fully armed MILF rebels about 5:30 a.m. Sunday at Upper Cabengbeng village. \"Five died on the spot while eight others were wounded in that ambush,\" said Sakalahul. Military regional spokesman Lt. Col. Randolf Cabangbang of Western Mindanao Command said the military was trying to ascertain the motive of the attack if it was related with the attacks staged by the rebels. Police and military have intensified the security in the region as the MILF rebels escalated their hostilities in Zamboanga peninsula. The Moro Islamic Liberation Front has been fighting government troops for decades to establish a self-rule Muslim sub-state in the south of the predominantly Catholic country. Peace talks between the government and the MILF stalled in August 2008 following the aborted signing of the Memorandum of Agreement on Ancestral Domain. A final peace deal with the government will touch the issues of autonomy and the civil settlement of the rebel group\'s 11,800-strong guerrilla fighters.