Police say two girl suicide bombers blew themselves up at a checkpoint outside Nigeria's northeastern city of Maiduguri and wounded three civilians.

Police spokesman Victor Isuku says the teenagers detonated their explosives when they were stopped for a search Sunday night about 12 kilometers (eight miles) east of the city center, near Muna bus station. 

That area has suffered several suicide bombings in recent weeks.

Isuku blames Boko Haram, the Islamic extremist group that has used scores of women and girls in suicide bombings. Some observers suspect that the women and girls are among the thousands Boko Haram has kidnapped over the years.

The seven-year uprising has killed more than 20,000 people, forced 2.6 million from their homes and created a massive humanitarian crisis, with 5 million people facing starvation.

AP