The bomb rocked Maiduguri's largest roundabout near the crowded Monday Market where elderly women line the road selling peanuts and kola nuts as snacks to morning commuters.
The defence ministry said in a tweet that an "improvised explosive device" went off in "a van loaded with charcoal" and that the area had been cordoned off.
Unruly crowds tried to attack firefighters deployed to the scene, accusing of them of arriving too slowly and hindering their efforts to put out the raging blaze, an AFP photographer said.
