RNA - Vigilantes said an individual suspected of working for the Boko Haram Takfiri terrorist group blew himself up amid worshippers inside the mosque in the town of Gamboru in the state of Borno at about 5:00 a.m. local time (0400 GMT) shortly before dawn prayers.
"Fourteen bodies have been pulled out of the rubble," said Umar Kachalla, a vigilante, adding that the mosque had been completely destroyed.
"Only the muezzin has survived and we believe more bodies are buried under the debris," said Kachalla. "The death toll may likely rise."
Another vigilante, Shehu Mada, reported that a patrol by his peers had detected four suspected bombers in the vicinity of Gamboru and arrested one of them after a chase an hour before the attack was carried out. "Two of them turned back and fled while the fourth disappeared into the darkness and we believe it was he who attacked the mosque," Mada added.
Nigeria has been suffering from deadly attacks claimed by Boko Haram in northeastern regions since 2009. At least 20,000 people have so far lost their lives in the attacks and more than 2.7 million others have been displaced.
The United Nations has already warned that areas affected by Boko Haram face a humanitarian crisis.