KIDAPAWAN CITY, Philippines, Jan. 4 (UPI) — A manhunt is underway on Wednesday in the southern Philippines after up to 158 inmates escaped from a jail following a raid by suspected Muslim rebels, officials said.

Philippines Bureau of Jail Management and Penology spokesman Xavier Solda said the inmates fled from Kidapawan City’s North Cotabato District Jail after more than 100 armed men attacked the facility at about 1:15 a.m. A firefight lasted for two hours, in which one jail officer was killed and another was injured.

The inmates housed in the dilapidated, mostly open-air facility escaped through the back portion of the jail as the firefight occurred. Solda said two inmates have surrendered, at least 14 escapees have been apprehended, while six have been killed, CNN reported.

Acting Provincial Jail Warden Superintendnet Peter Bungat said members of a rebel group fighting for an autonomous region for Muslims in the Philippines’ southern island of Mindanao were responsible for the raid.

The group that took part in the attack seemed to be members of breakaway faction Moro Islamic Liberation Front, a group that sought peace with the government.

The escapees “are mostly our Muslim brothers and most of them are [Moro Islamic Liberation Front] members,” Bungat said. “But the others likely just went along with the jailbreak.”

Bungat said the attack was “well planned,” adding that at least a dozen inmates who fled were jailed on drug-trafficking charges.

A spokesman for President Rodrigo Duterte said there was no “specific information” on the gunmen’s identity.