A suicide bomber has killed five people and wounded dozens in Potiskum in the third such attack to hit the town in northeastern Nigeria this month.
There was no immediate claim of responsibility for Sunday's attack on a bus station, but suspicion immediately fell on Boko Haram.
Boko Haram opposes Western education and wants to impose Islamic law in all 36 states of Nigeria, which is roughly equally divided between a predominantly Muslim north and a mainly Christian south.
The group operates mainly in the northeastern Nigerian states of Adamawa, Borno and Yobe, where the government has declared a state of emergency since May 2013.
Last Sunday, Potiskum was the scene of a bombing in a crowded market carried out by two female suicide attackers, one believed to be aged around 15.
Witnesses to Sunday's latest attack said the explosion targeted the bus station at Tashar Kunne, on the outskirts of Potiskum, at around 10:30am local time (09:30 GMT).
A police officer said four bodies and 48 injured people had been taken from the scene.
A nurse at the Potiskum General Hospital gave a similar death and injury toll, and said local residents had rushed to the hospital in search of their loved ones.
She described the suicide bomber as a young man.
Raids, massacres, suicide-bomb attacks and kidnappings by Boko Haram have claimed at least 13,000 lives and driven an estimated 1.5 million people from their homes, mainly in arid northeast Nigeria.
Neighbouring Cameroon, Chad and Niger have launched a regional bid to combat the fighters, as their attacks spread beyond Nigeria and concern mounts over the failure of Nigerian authorities to regain control.