A suicide bomb attack on a mosque in northeastern Nigeria has killed at least 11 people, according to reports.
Witnesses said the bombing took place as worshippers were attending morning prayers.
"I was on my way to dawn prayer, then I heard the sound of a loud bomb explosion inside the mosque," aid worker Ali Mustapha told Reuters news agency.
"The mosque was destroyed and burned," added Mustapha.
"After some hours, when we came to evacuate the people, we saw 11 corpses, with the suicide bomber making [the total number of dead] 12."
No group has claimed responsibility so far, but the area and type of attack bear the hallmarks of Boko Haram, whose name roughly translates to "Western education is forbidden".
The group has waged an armed campaign in northeastern Nigeria since 2009.
The conflict has left at least 20,000 people dead and displaced more than 2.6 million.
Last week, more than 700 people abducted by Boko Haram in Nigeria escaped from captivity. The captives included farmers, fishermen and members of their families, a spokesperson for the Nigerian army said.
At its peak, the group controlled large swaths of territory in the Lake Chad region, but the Nigerian military, with assistance from Chad, Cameroon and Niger, has pushed its fighters out of a number of provinces in the northeast.
Despite the pushback from the international coalition, Boko Haram remains active in the area, often carrying out suicide attacks against civilians.
In early December, at least 17 people were killed in the city of Biu when two suspected Boko Haram suicide bombers detonated themselves at a market.
That attack came only two weeks after a teenage suicide bomber struck a mosque in Mubi, killing at least 50 people.
Source: Al Jazeera and news agencies