Suicide bombers killed 17 people and injured 21 in the northeast Nigerian city of Maiduguri, the police commissioner of Borno state said on Wednesday.
The blasts struck four areas in the city, which is the capital of Borno, the state worst affected by the eight-year-old insurgency by Islamist militant group Boko Haram.
The Boko Haram insurgency has killed more than 15,000 people since 2009 and forced some two million to flee their homes.
The Nigerian army, backed up by neighbors, have retaken most areas held by the group. But the jihadists still operate in the area of Rann, slipping over the porous Cameroon border after attacks.
The militant group has stepped up attacks and suicide bombings in the past few weeks as the end of the rainy season facilitates movement in the bush.