An election rally attended by Nigerian President Goodluck Jonathan was hit by a suicide bomb, killing at least one and injuring 18.
The rally, in the northern city of Gombe, was held in advance of the presidential election on February 14, where Mr Jonathan will face the former military ruler Muhammadu Buhari.
According to residents, the president left the rally three minutes before the explosion.
A local journalist told AFP the explosion had led to unrest in Gombe, with angry youths attacking supporters of Mr Jonathan's People's Democratic Party (PDP).
"They were shouting and denouncing the president's visit which they blamed for the attack," he added.
Nigeria's Boko Haram militants have recently stepped up attacks on government targets and are attempting to capture Maiduguri, a strategic city in the Borno state.
The Chadian air force meanwhile has continued to carry out attacks on Boko Haram positions around Gamboru, near the Cameroonian border.