Boko Haram Islamists claimed five lives in an attack on a mosque in northeast Nigeria over the weekend, before being repulsed by soldiers who killed 15 of the insurgents, the military said in a statement Sunday.
The latest attack by the extremist group, which has been waging an insurgency since 2009, struck on Saturday morning at Damboa town in Borno state, the group's stronghold.
"The terrorists... attacked worshippers in a mosque and killed five of them who came to perform their morning prayers," said the military's statement quoting captain Aliyu Ibrahim Danja, army spokesman for the region.
"They also set ablaze the official residence and palace of the District Head along with some shops.
"While they were unleashing their mayhem, troops under 7 Division engaged the terrorists, killing 15 in the process while others fled in disarray."
Borno was placed under a state of emergency in mid-May, when the military shut down the mobile phone network to block Islamists from coordinating attacks in an operation aimed at crushing the insurgency.
With the communication network switched off, details of attacks have been slow to emerge and difficult to verify.
Boko Haram has said it is fighting to create an Islamic state in northern Nigeria, but its aims have shifted and the group is believed to consist of different factions.
The group has attacked churches, mosques, schools, newspaper offices, the security forces, politicians and a UN building, among other targets.
The Boko Haram conflict is estimated to have cost more than 3,600 lives since 2009, including killings by the security forces, who have been accused of major abuses.