MANILA, Philippines (AP) — About a dozen gunmen armed with grenades and bombs stormed a southern Philippine jail in an attempt to spring a detained comrade, but were repulsed by police in a chaotic night attack that killed three people, officials said Monday.

Fifteen people were wounded, most of them civilians caught in the firefight outside Kidapawan’s city hall compound and along a key commercial road. Police blamed former members of the Moro Islamic Liberation Front, but a spokesman for the rebel group denied the claim.

The attackers fired a grenade into the gate of the Kidapawan city jail in North Cotabato province but missed around 10 p.m. Sunday, sparking a gunfight with guards who were later reinforced by nearby police forces. The gunmen detonated a bomb and fired on civilians as they withdrew toward a mountainous region late Sunday, police said.

At least three people died, including a Red Cross driver who was trying to bring wounded civilians to a hospital, regional police director Chief Superintendent Benjardi Mantele said.

Kidapawan police chief Chino Mamburam told The Associated Press that the attackers were believed to be former members of the Moro Islamic Liberation Front who wanted to rescue a comrade detained for robbery and other crimes.

Mamburam said the assault failed because guards had bolstered security at the jail before the attack after being warned by police that Muslim rebels were planning an assault. Jail guards were also rapidly reinforced by police from a nearby station, he said.

Government forces were pursuing the attackers, he said.

Rebel spokesman Von al Haq denied his group was involved in the attack.

He said that the attackers were not members of the Moro group, which has been focusing on yearslong peace talks with the Philippine government and has forged an accord that allows the rebels to help the government track and capture criminals and al-Qaida-linked militants.