Around 100 armed men with links to Muslim rebels stormed a prison in the southern Philippines on Wednesday, killing a guard and freeing more than 150 prisoners, some of them Islamic militants, officials said.

The Southeast Asian, majority Roman Catholic nation has for decades been plagued by insurgency by Muslim rebels in its southern islands.

The gunmen opened fire at guards at the North Cotabato District Jail in Kidapawan, prison warden Peter Bongat said on radio. Of the jail’s 1,511 inmates, 158 managed to escape, he said.

Eight prisoners had since been caught, two had surrendered, while six were killed, according to the office of the president.

Shirlyn Macasarte, acting governor of North Cotabato, said her office had been tipped off about the plan by the Bangsamoro Islamic Freedom Fighters (BIFF) to free its members as early as the second quarter of last year.

“They were involved in murders and at the same time I think they have experience in bomb making so we watched them closely,” Macasarte told news channel ANC.

The leader of the attackers, known by the alias Commander Derbie, had links with the BIFF, a splinter group of the Moro Islamic Liberation Front (MILF), Macasarte said.

Some members of the MILF and BIFF were said to be behind the killing of 44 police commandos in a secret mission two years ago to capture a Malaysian bomb maker with a $5 million bounty from the U.S. State Department on his head.

Story by Reuters