Armed men with links to the Philippines’ largest Muslim rebel group have stormed a prison in the south of the country, killing a guard and freeing more than a 150 inmates, police said.

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.

Of the jail’s 1,511 inmates, 158 managed to escape and four were recaptured, he said.

“It’s well planned. Escapees used blanket as their getaway...We have a manhunt operation,” said Bongat.

Unconfirmed reports by Filipino officials suggested that the raid was carried out by Satar Mandalondong, a MILF commander.

“What we know at the moment is that the army had to send reinforcements to mitigate the forces of the Philippine National Police that have been pursuing the armed group that led the jailbreak,” said Al Jazeera’s Jamela Alindogan, reporting from Manila.

“We have reports that there have been fatalities [as a result of the operation],” she said.

“We have spoken to forces on the ground, they said they had body counts but until now the Philippine government has not released official statistics but we know that shelling is still ongoing.”

The MILF group has not claimed responsibility for the jailbreak.

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. (Al Jazeera/News agencies)

Update news