MANILA — A manhunt was underway Wednesday for more than 150 inmates who escaped from a jail in the southern Philippines after it came under attack by gunmen overnight.

One guard was killed and another wounded in the assault on a jail in Kidapawan City on the violence-plagued southern island of Mindanao, according to Peter Bungat, the warden. The gunmen were thought to be from a bandit group that had broken away from a Muslim rebel organization, Mr. Bungat told a radio station on Mindanao, which is home to a decades-old insurgency.

Five of the 158 inmates who escaped from the facility, the North Cotabato District Jail, were later killed in a shootout with pursuing officers, Senior Inspector Xavier Solda, a spokesman for the Philippine Bureau of Jail Management and Penology, told a radio station in Manila. A village official was also killed when he was mistaken for one of the escaped inmates, the police said.

Mr. Bungat said the attack began early Wednesday, when the jail’s power supply was cut. Armed men then approached from behind the compound and began firing. “It was well planned,” Mr. Bungat said.