|Maiduguri has been the scene of several attacks this year [EPA]
A series of suicide bombings and roadside bombs have hit the city of Maiduguri while gunmen attacked the cities of Damaturu and Potiskum, all in the northeastern region of Nigeria, officials have said.
There was no immediate claim of responsibility for the attacks on Friday but authorities said they suspected Boko Haram, a radical Muslim group of fighters, who have carried out a succession of recent attacks in the country, was responsible.
"One soldier and six civilians have been injured by the three suicide bombers in multiple blasts [in Maiduguri]," Lieutenant Colonel Hassan Mohammed, commander of the Joint Military Taskforce for Borno state, told the Reuters new agency.
The series of attacks in Maiduguri began when three roadside bombs exploded in quick succession in an apparent co-ordinated strike, hitting the wards of Meduguri and Jajeri and the El-Kanemi College of Islamic Theology, all of them around the time of Friday prayers, causing panic in the mosques.
A short time later, suicide bombers driving a black SUV attempted to enter a base for the military unit charged with protecting the city from Boko Haram fighters, a military spokesperson told the AP news agency.
The SUV could not enter the gate and those inside the vehicle detonated explosives outside the base, damaging several buildings in the military's compound, according to Hassan Ifijeh Mohammed, an army spokesman.
Running gun battles
Gunmen later attacked the towns of Damaturu and Potiskum, located next to each other about 100 km west of Maiduguri, in Yobe state, and engaged in running gun battles with security forces, witnesses told the Reuters news agency.
Residents heard several explosions, which later turned out to be the bombings of small local churches and a police stations.
Security forces this week started door-to-door searches for weapons in the northeast, after an arms amnesty for fighters expired on October 31. It was unclear whether or not this spate of attacks was a response to that operation.
Boko Haram, which means "Western education is sacrilege", has staged numerous targeted assassinations and bombings around Maiduguri over the last year, killing more than 240 people this year alone, according to AP figures.
In recent months, the group appears to have abandoned some of its previous restraint in only targeting government and security officials.
In August, it claimed responsibility for the suicide car bombing of the United Nations headquarters in Nigeria's capital Abuja, which killed 24 people and left another 116 wounded.