Spokesperson of the Borno state police command, Victor Isuku, said the attackers were a male and two teenage girls believed to be working for Boko Haram, Nigeria's homegrown Islamic extremism rebels.
Isuku, a deputy superintendent of police, said one member of the civilian militia, a woman and two children were killed and 8 others were injured.
He said the bombers infiltrated Maiduguri by sneaking in during the dark hours, but were spotted by members of the civilian self-defense group on sentry duty. The three then detonated their explosives.
Suicide bomb attacks have almost become a daily occurrence around Maiduguri recently.