New clashes are reported in northeastern Nigeria, where militants raided a state capital late Thursday. Meantime, the army says it killed more than 70 militants in a different location.
The region is the center of the Boko Haram insurgency, blamed for thousands of deaths over the past four years.
Suspected Boko Haram fighters entered the town of Damaturu, capital of Yobe state, late afternoon Thursday, and, according to Nigerian newspapers, attacked police and security buildings.
Police and soldiers exchanged gunfire with the militants Friday morning, according to one resident.
A spokesman for the military's Joint Task Force, Capt. Eli Lazarus, declined to give casualty figures for either side.
Authorities have since imposed a 24-hour curfew in Yobe state.
Meanwhile, the Nigerian army says 74 Boko Haram fighters were killed during an air-and-ground assault Thursday in nearby Borno state.
Military spokesman Lt. Col. Muhammed Dole says the operation in the Mainok area destroyed a terrorist camp and several vehicles. He says two soldiers were wounded.
There has been no independent confirmation of the attack.
Boko Haram has been fighting since 2009 to impose a strict form of Islamic law on Nigeria's Muslim-majority north.
The group continues to launch attacks in the northeast, despite an all-out government military offensive ordered by Nigerian President Goodluck Jonathan in May.