It said 105 prisoners were freed in the pre-dawn raid in Bama, Borno state. Bama's police station, military barracks and government buildings were burned to the ground, said the military and witnesses. Correspondents say extremist attacks are common in the region but the scale of bloodshed makes this raid stand out. This strike - coming on the back of other deadly attacks - undermines the suggestion that the military operation against the militants has diminished the threat they pose, says the BBC's Will Ross in Lagos. President Goodluck Jonathan has set up a committee to agree the terms of an amnesty for the rebels but Boko Haram's leader, Abubakar Shekau, has so far rejected the idea. Tuesday's raid in the remote town began when some 200 heavily-armed suspected members of Boko Haram arrived in buses and pick-up trucks at about 05:00 (04:00 GMT), said Musa Sagir, a military spokesman based in Maiduguri, some 70km (44 miles) from Bama. "Some of the gunmen attacked the military barracks but they were repelled. Ten of them were killed and two were arrested," he told AFP news agency. "But the gunmen broke into the prison, freeing 105 inmates, and killed all prison warders they could see except those who hid in a store where cooking utensils were kept," he said. Some of the attackers wore army uniforms for the assault, which continued for almost five hours, he added.