A civilian self-defense commander says a suicide bomber has exploded outside a bus station in Nigeria's northeastern city of Maiduguri, killing himself and one other person.

It is the sixth attack in four weeks on the city that is the birthplace of the oko Haram Islamic extremist group. Most attacks have been foiled with the bombers killing only themselves.

Cmdr. Habuya Mahmud of the Civilian Joint Task Force says Wednesday night's bomber was prevented from entering Muna Garage bus station but killed an innocent bystander. Last Friday, two suicide bombers blew up at Muna Garage, killing two self-defense fighters.

Boko Haram has stepped up attacks after a months-long lull in the 7-year-old Islamic uprising that has killed more than 20,000 people and forced 2.6 million from their homes.