Witnesses and a security official say an explosion hit a bustling market during the morning rush hour in Nigeria’s northeastern city of Maiduguri.
No immediate details were available about the blast blamed on Boko Haram Islamic extremists.
Bomb blasts last week hit the biggest shopping mall in Abuja, killing 24 people, and a medical college in Kano, killing at least eight.
Boko Haram has attracted international attention and condemnation since its April abduction of more than 200 schoolgirls from a northeastern town who remain captive.
Witnesses said the explosion ripped through the market early Tuesday. A security official at the scene confirmed the blast, saying many casualties are feared. Witnesses spoke on condition of anonymity for fear of reprisals, and the security official was not permitted to speak to press.