A gunman has attacked a Philippine army base on the island of Jolo, killing nine soldiers and a civilian.
Officials said they were unsure whether the gunman was a soldier or was the civilian found among the dead.
The unidentified attacker opened fire inside the base during a power cut, one report said.
Thousands of Philippine soldiers are based on Jolo, where they are fighting a Muslim rebel group, Abu Sayyaf, which has been linked to al-Qaeda.
Officials investigating the army base attack could not say whether there was any link to the group.
Abu Sayyaf is the smallest of four Muslim rebel groups in the Philippines, with about 400 members.
The island of Jolo is some 950km (600 miles) south of the Philippine capital, Manila.