Updated

Suspected Muslim militants attacked government troops guarding a school construction site in a rebel stronghold in the southern Philippines on Sunday, igniting a clash that killed 13 gunmen and two marines, a marine commander said.

About 50 gunmen attacked two marine detachments in hilly Talipao town in Sulu province at dawn, setting off two hours of fierce fighting that killed 13 suspected militants and two marines, marine commander Col. Romeo Tanalgo said. Six other military personnel were wounded before the gunmen split and withdrew into the forest, he said.

The attackers were likely young Muslim militants trained by the notoriously violent Abu Sayyaf, an Al Qaeda-linked group regarded as a terrorist organization by the United States and the Philippines, and radical members of a larger rebel group, the Moro National Liberation Front, which also has a presence in the impoverished, far-flung community, military officials said.

The militants have formed a new group called Awliyah and are led by a commander identified as Hatib Zacaria who wants to make a name through violence, said regional military spokesman Lt. Col. Randolph Cabangbang. The marines have been monitoring the new group for about a year.

The marines who came under attack in their two roadside detachments were guarding a school construction site and a road project.

"These are the people who are against development, that's why the mayor is mad," Tanalgo said of the militants, who were mostly armed with M16 assault rifles.

The clash halted a planned Muslim wedding in Talipao, angering many villagers, some of whom offered to help fight the militants. They were not allowed to join the clash, said another marine officer, who spoke on condition of anonymity because he was not authorized to talk to reporters.

Government troops recovered seven rebel firearms at the scene of the fighting and were checking if there were more bodies of slain gunmen in the area. Reinforcement troops were pursuing the fleeing militants, Tanalgo said.

Washington blames the Abu Sayyaf for many bomb attacks, kidnappings for ransom and beheadings. The militants have attacked and killed American citizens in the past and have been the target of yearslong U.S.-backed Philippine offensives.

The Moro National Liberation Front signed a peace accord with the government in 1996 after it dropped its secessionist bid and settled for limited Muslim autonomy in the south, homeland of minority Muslims in the predominantly Roman Catholic Philippines.

Most of the Moro rebels, however, did not lay down their arms and now complain that the Philippine government reneged on many political and economic promises under the 1996 pact. They have occasionally been blamed for launching attacks against government forces and have been suspected of harboring Abu Sayyaf militants in Sulu, about 610 miles (980 kilometers) south of the capital, Manila.

The Philippine government has been in talks with Moro National Liberation Front rebels to address their complaints after they made a pledge not to coddle the brutal Abu Sayyaf.