Clashes between Nigerian armed forces and Islamists after a daring attack on the military in the country's restive northeast left 53 insurgents and six troops dead, a spokesman said.
The rebels attacked barracks and a police station in the town of Damboa, in Borno state, late on Friday while most of the troops were out on patrol in surrounding villages, drawing an army response, defence spokesman General Chris Olukolade said in a statement on Saturday.
Five soldiers and a senior officer were killed while repelling the attack.
The area was cordoned off and searched, while the bodies of the fallen soldiers were recovered and taken to a military morgue. The wounded were treated at a military medical facility.
"Half of Damboa has been burnt, including the police station. People are just fleeing the town," said a resident reached by telephone who requested anonymity.
Others said the military had seized four armoured carriers.
"The soldiers gave the Boko Haram fighters a good fight and took over the four APCs they came with," said one. "The soldiers also suffered casualties."
"Many homes were burnt in the attack. Many residents have fled the area. The police station was also burnt", another resident said.
Witnesses estimated that the toll among civilians and the armed forces could be higher than that given by the army.
Security experts say the overstretched and under-resourced military is incapable of fighting an effective counterinsurgency against Boko Haram militants, who have killed thousands in their five-year campaign for an independent Islamic state in the north.
Also on Friday, a suicide bomber rammed his car into a checkpoint at Konduga, Borno state, killing a policeman and three militiamen, Olukolade said.