The sailors were aboard ship MV Giang Hai with 25crewmembers, which was attacked near Baguan Island in Tawi-Tawi, an area closeto the stronghold of the notorious Abu Sayyaf militant group.
According to Reuters, other 17 Vietnamese sailors on boardwere rescued by the Philippine coastguard and marine soldiers.
An investigation was underway and the coastguard hadlaunched a pursuit in coordination with the military and police, said Philippinecoastguard spokesman Armand Balilo.
Abu Sayyaf group, which has a close link with the IslamicState, is believed to be the culprit of the attack. Well armed and equippedwith fast boats and high-tech navigation devices, the group has conducted frequentpiracy attacks and kidnapping for ransoms.-VNA