Regional military spokesman Lt. Col. Randolph Cabangbang said the attackers belonged to an armed Muslim group with links to the Al-Qaeda-linked Abu Sayyaf and the larger Moro National Liberation Front in Talipao town in Sulu province.

Cabangbang says about 50 gunmen attacked marines guarding a US-funded school construction project in Talipao Sunday. The clash killed 13 gunmen, two marines and two villagers.

The US Embassy spokeswoman Tina Malone says the violence caused work to be suspended at the school site.

Malone says despite the violence, Washington will continue to work with Manila for Sulu’s development.