Police in Nigeria said Thursday that militants attacked a prison and freed several inmates in the central part of the country.

Witnesses said around 20 gunmen on motorcycles attacked the federal prison just south of Abuja late Wednesday, firing at guards before setting off a bomb outside the main gate. They said one guard was killed, while the others fled during the battle.

Local reports said the radical Islamist group Boko Haram is responsible for the attack. Witnesses said the gunmen specifically freed members belonging to the group, while the remaining inmates appeared to escape during the unrest.

Also Wednesday, Nigerian authorities said that an ex-soldier is wanted in connection with the Christmas Day bombing of a church in Abuja that left dozens dead.

The suspect, Habibu Bama, was reported to be an accomplice of Kabiru Sokoto, who was recaptured earlier this month after initially escaping custody with the help of Boko Haram.

The group is blamed for hundreds of deaths in bombings and shootings over the past 18 months, mostly in northern Nigeria. Much about the group remains unknown, but it is believed to want wider implementation of sharia, or Islamic law.