Two towns in nothern Nigeria have been hit by two seperate attacks, killing at least 12 people, eyewitnesses have said.
In the first attack on Wednesday, soldiers opened fire on a female suicide bomber when she refused to be searched as she approached army barracks in Bolari, in Gombe state, detonating the explosives belt she was wearing, according to eyewitness accounts.
"The woman refused to stop and continued to advance towards the military guards at the gates despite repeated orders from them to stop at a distance," said Shuaibu Nasir, who lives near the gates of the barracks.
We heard a series of explosions from the bus which went flying into the air in flames
"The soldiers opened fire on the woman who quickened her pace towards them and as they fired shots at her she exploded with a loud sound that shook our buildings," Nasir said.
In another attack on Wednesday, witnesses said that 11 people were killed when a bus exploded in the town of Fika in northern Yobe state.
"We heard a series of explosions from the bus which went flying into the air in flames," said Usman Haruna, a resident.
No official confirmation of the death toll has been given.
Nigeria's northeastern Gombe state has been the scene of several attacks by armed group Boko Haram in recent months, and the same barracks were targeted in July.
Northeast Nigeria has been continually rocked by attacks mounted by Boko Haram fighters, increasingly using female suicide bombers.
The group has killed thousands since it began its insurgency in northern Nigeria five years ago.
Experts have cast doubt on Nigeria's ability to hold planned presidential elections in February, because of rising unrest in parts of the northeast.