More than 100 suspected Muslim rebels have stormed a jail in the southern Philippines, killing a guard and allowing 158 inmates to escape, officials said.

Six of the inmates were killed in firefights with pursuing police and army troops, while eight others have been caught and were being returned to the facility, said Senior Inspector Xavier Solda, spokesman for the Bureau of Jail Management and Penology.

Initial reports suggested that the gunmen responsible for Wednesday’s jailbreak were linked to the Moro Islamic Liberation Front (MILF), officials said.

The attackers opened fire at guards at the North Cotabato District Jail in Kidapawan city around 1am, prison warden Peter Bongat told a local radio station.

The jail held 1, 511 inmates at the time, he said.

“When the attack came, according to the report of the Bureau of Jail Management and Penology, it was a two-hour firefight” said Dionardo Carlos, Philippine National Police Spokesperson.

“The jail guards were trying to stop the attackers and then our police responded,” he said at a press conference.

“Unfortunately, because of the commotion, some inmates escaped using a wooden ladder that they stuck to the wall at the back portion of the jail.”

No claim of responsibility

Unconfirmed reports by Filipino officials suggested that the raid was carried out by Satar Mandalondong, a MILF commander. But the MILF group has not claimed responsibility for the jailbreak.

The MILF is the largest Muslim rebel group in the Philippines and it is based in the southern region of Mindanao. The group demands more autonomy for the Moro people.

The predominantly Catholic Southeast Asian nation has for four decades been fighting rebels in its southern islands.

Wednesday’s incident was the latest of several mass escapes from poorly secured Philippine jails, with the incidents often involving southern rebels.

In August, another rebel group called Maute staged a jailbreak in the southern Philippines, freeing 23 detainees.

About 50 heavily armed members of the group raided the local jail in the southern city of Marawi on Mindanao island and freed eight of their members who were arrested a week earlier, police said.

In 2009 more than 100 armed men raided a jail in the strife-torn southern island of Basilan, freeing 31 prisoners including several guerrillas.

The conflict between the rebels and the state in southern Philippines has left more than 120,000 people dead in the last four decades.

President Rodrigo Duterte is pursuing peace talks with the largest armed Muslim groups, the Moro National Liberation Front (MNLF) and the MILF.

Smaller bands like the Maute group and the Abu Sayyaf group are not covered by the ceasefires and are not part of the peace process.