At least 50 people have been reportedly killed in a suicide bombing attack in Adamawa state, police say.
The bomber struck inside a mosque packed with worshippers during morning prayers in the northern town of Mubi.
Witness Abubakar Sule told AFP news agency that it appeared the bomber was part of the congregation.
No-one has claimed responsibility for the attack but fingers point at the Islamist militants Boko Haram.