A female suicide bomber has blown up herself in northern Nigeria's Gombe city, minutes after President Goodluck Jonathan left a campaign rally there.

Nigeria elections: Blast hits Jonathan rally in Gombe

At least one person was killed and 18 others were wounded in the blast, police and hospital sources said.
Mr Jonathan is standing for re-election on 14 February against former military ruler Muhammadu Buhari.
Militant Islamist group Boko Haram has stepped up its attacks in the run-up to the contest.
It has not commented on the blast.
Explosions have also ripped through court buildings in three towns in oil-rich southern Nigeria in what police described as co-ordinated attacks.