A girl thought to be as young as seven has killed herself and another seven people in a bomb attack at a market in Potiskum, a town in Yobe State.
Nineteen people injured in the blast were taken to hospital, a local vigilante leader, Buba Lawan, told AFP.
No group has claimed responsibility for the attack, but suspicion is likely to fall on terror group Boko Haram, which often carries out its bloody campaign in Yobe and other states in northern Nigeria.
Who are Boko Haram militants?
Boko Haram, which fights against Western influence in Nigeria and aims to impose its version of Sharia law in the country, declared an Islamic caliphate in Gwoza, along the Cameroon border, in August 2014.
The group has been raiding several cities in the north of the country in a bid to take control of more land.
Three states, Adamawa, Borno and Yobe, have been under a state of emergency since May 2013, due to Boko Haram's deadly attacks.
The group is renowned for using children in its attacks, particularly after it kidnapped some 220 schoolgirls in Borno state last April.
Shortly after the mass abduction, reports emerged that female suicide bombers had increased throughout northern Nigeria.
In February, a female suicide bomber detonated a device at a bus station in the city of Damaturu, capital of Yobe State, killing at least 10 people.
The blast in Potiskum is only the latest of a series of attacks carried out by the insurgents while Nigerian President Goodluck Jonathan postponed presidential elections by six weeks amid security concerns.
Some have criticised the delay, arguing that Jonathan is trying to gain more votes and defeat the opposition.
Others hope that the six week-delay could allow African Union forces - comprising troops from Nigeria, Chad, Benin, Cameroon and Niger - to combat Boko Haram and recapture territories occupied by the insurgents.