Nigeria's military said its forces have repelled a second attempt in a week by Boko Haram fighters to take over the key northeastern city of Maiduguri.
Military officials said Sunday's attack, which started about 3 a.m. (0200 GMT), on Maiduguri was contained, more than 12 hours after Boko Haram laid siege to the city from four different roads.
Maiduguri in Borno state, Nigeria
Heavily-armed gunmen set off explosives as they tried to enter the city, several residents said.
The officials said many militants were killed during the fighting in the capital of Borno state. Several civilians also died. A hospital source reported eight bodies had been brought in from the fighting.
A VOA reporter, Abdulkareem Haruna, saw hundreds of civilians armed with hunting rifles, clubs and machetes advance toward the battles, saying they want to help the soldiers stop the militants.
Separately, a suicide bomber killed seven people in Potiskum, the economic capital of neighboring Yobe state, while two blasts - one also carried out by a suicide bomber - killed five people in Gombe city to the south.
These incidents come two weeks before Nigeria's February 14 general election. Election officials have conceded that voting will be impossible across much of the northeast.
President Goodluck Jonathan faces a stiff challenge from former military ruler Muhammadu Buhari.
Analysts have said Boko Haram will likely make another attempt to take over Maiduguri before that poll. The militant group tried to capture Maiduguri a week ago, but failed.
Despite waves of attacks in the city in recent months, Maiduguri has become a place of refuge for people forced to flee other areas in Borno that have been taken over by the Islamist rebels.
On Saturday, Chadian forces reclaimed the northeastern Nigerian town of Gamboru-Ngala, after a heated battle with Boko Haram that involved a ground and air campaign. Gamboru-Ngala, about 145 kilometers east of Maiduguri, was captured by Boko Haram last year.
A soldier involved in the operation said Chadian forces were working under the African Union agreement for member states to help Nigeria in its fight against Boko Haram.
Increase in violence
The African Union on Saturday agreed to move forward with a proposal to send 7,500 troops to fight the Boko Haram insurgency.
The conflict has forced more than 1 million people from their homes and killed some 10,000 people in the past year alone, according to the Council on Foreign Relations.
The Nigerian army has struggled to contain Boko Haram, which has said it is taking territory for a caliphate ruled by Islamic law.
Last April, Boko Haram sparked international outrage when it kidnapped 276 schoolgirls from the remote Nigerian town of Chibok. Dozens have managed to escape, but more than 200 remain missing.
Some material for this report came from Reuters, AFP and AP.