A young female suicide bomber killed 12 worshippers when she blew herself up in a mosque in northeastern Nigeria, a witness and a vigilante assisting the military in the fight against Boko Haram said Friday.

"While the people were inside the mosque for the prayers she ran from a distance into the mosque and blew herself up," vigilante Danlami Ajaokuta said of Thursday's attack in Malari village, adding 12 had died and seven were injured.