Suicide bombers carried out a series of attacks Tuesday night in the northeastern Nigerian city of Maiduguri, killing at least 17 people.
Four bombers, including at least one female, targeted the civilian self-defense force and mourners who had gathered around them, according to the Associated Press. In addition to the dead, which includes the bombers, at least 21 people were injured.
Maiduguri is the capital city of Borno, the Nigerian state that has been most affected by the eight-year insurgency of the Islamist militant group Boko Haram.
Borno state police commissioner Damian Chukwu told the AP that the majority of those killed were members of the self-defense force.
"A teenage female suicide bomber actually crept to the sandbag post of our boys at Molai, and before they could realize what was happening, she detonated herself and killed three of our boys," defense force spokesman Danbatta Bello told the AP. "That happened simultaneously with the one that occurred at the tea vendors, where seven of our members who took their time off to eat their dinner were killed."
Some young women who have escaped Boko Haram say the group drugs girls and forces them to carry out suicide bombings, the AP reports.
Nigeria's president said in December that troops were dealing "the final crushing of Boko Haram terrorists in their last enclave," but attacks have continued.
In late June, three suicide bombers struck a university in Maiduguri; four female suicide bombers then struck two villages near the city, killing 12. The government of Borno began digging a 17-mile trench around the university in hopes of preventing further attacks by Boko Haram.
Reuters reports that the Boko Haram has killed more than 20,000 people and sent 2.7 million people from their homes. The United Nations says some 5.2 million people in the country are food insecure and estimates that 450,000 children younger than 5 suffer severe acute malnutrition in Borno and the neighboring states of Adamawa and Yobe.