ZAMBOANGA – Gunmen opened fire on a commuter bus in the restive southern Philippines, killing two and wounding eight passengers, authorities said Thursday.

The bus was strafed along a coastal highway shortly after leaving Gutalac town in Zamboanga del Norte province on Wednesday, said regional military spokesman Major David Hontiveros.

Two passengers died and eight others were treated in a hospital for gunshot wounds, he said.

It was not clear who was responsible for the attack. The gunmen fled, leaving behind empty bullet shells, he said.

The predominantly Roman Catholic nation's south has been wracked by a decades-long Muslim insurgency. Communist guerrillas and criminal gangs also are active.

Last month, armed kidnappers snatched Irish Reverend Michael Sinnott, 79, in neighboring Zamboanga del Sur province, and demanded $2 million for his release. The government has rejected the demand.