A suicide bombing in the northeast Nigerian town of Biu killed about 19 people and injured 17, a day before the president made a visit to another town in another state hit by violence.

The bodies and remains of about 20 people were brought to the hospital in the town in Borno state after Wednesday's attack, said Nasiru Buhari, a member of the Civilian Joint Task Force, formed by residents to fight against Boko Haram.

The suicide bomber may have been heading toward Biu market, but could not get past security points set up by the Civilian JTF, witnesses said.

A security official, who spoke on condition of anonymity because he was not permitted to speak to the press, confirmed the bombing.

On Thursday, Nigerian President Goodluck Jonathan made an unannounced visit to Mubi in the northeastern Nigerian state of Adamawa. The Nigerian military reclaimed Mubi in November after Boko Haram fighters had seized it in October, renaming the town "Madinatul Islam," meaning "City of Islam."

The president met with soldiers and the traditional ruler, residents said.

The President's visit to the former Boko Haram stronghold comes a day after the Nigerian army chief visited Baga, another town that was previously overtaken by Boko Haram.

Lt. Gen. Kenneth Minima traveled to Baga on Wednesday and later told journalists that residents displaced by Boko Haram should be able to return to vote in the March 28 presidential election.

President Jonathan is in the midst of a close re-election bid, running against ex-military ruler Muhammadu Buhari.

Nigerian defense officials have announced recent victories in the fight against the insurgents, claiming to have recaptured towns across the embattled northeast, where Boko Haram's insurgency has displaced an estimated 1.6 million.

The United States Senate this week voted unanimously to condemn attacks perpetrated by Boko Haram against innocent civilians, according to a statement. It also called on Nigeria's government to ensure that upcoming national elections on March 28 and April 11 are safe, credible, and transparent.