Gunmen killed 15 fishermen in the southern Philippines in an attack at sea suspected to have been triggered by a dispute between rival fishing groups, the military said Tuesday. Three fishermen were also wounded Monday off Sibago Island, which is part of Basilan province, 900 kilometres south of Manila, according to a report of the German Press Agency "DPA". The fishermen were aboard three boats when the suspects opened fire on them, said Lieutenant Colonel Randolph Cabangbang, a regional military spokesman. Cabangbang said the navy dispatched teams to pursue the perpetrators and police were looking into the possibility that the attack was triggered by a rivalry among local fishermen. "In Basilan, the fishermen maintain turfs. If you intrude into their turf, you will be in danger," he said.