“Muslim militants disguised as policemen and soldiers detonated bombs and opened fire Tuesday in a series of coordinated attacks in a southern Philippine city, triggering clashes that killed at least 12 people.

About 25 Abu Sayyaf militants were involved in the attacks in Isabela city on the island province of Basilan, one of the most daring operations by the al-Qaida-linked group in recent months, regional military commander Lt. Gen. Benjamin Dolorfino said.

The dead included three marines and three militants, including an Abu Sayyaf commander identified as Bensar Indama, who wore a police uniform. A policeman and five civilians were also killed, including one who died in a hospital in nearby Zamboanga city after being airlifted from Basilan, Dolorfino said.

“Philippines authorities Tuesday started evacuating about 50,000 people living around the island nation’s most active volcano after it oozed fiery lava and belched clouds of ash.

A large-scale eruption was forecast as imminent.