Manila  - Three civilians were killed and three wounded when suspected communist rebels attacked a cargo truck in the central Philippines, a town police chief said Monday.

The victims were aboard a cargo truck on a highway in Toboso town in Negros Occidental province, 570 kilometres south of Manila, when the gunmen fired at them Sunday, Senior Inspector Nestor Tuadles said.

Tuadles said the injured were taken to a nearby hospital where they are being treated for gunshot wounds.

Investigators were trying to determined the motive behind the attack.

Communist rebels have been fighting the government since the late 1960s, making the movement one of the longest-running leftist insurgencies in Asia. (dpa)