Kano, Nigeria (CNN) -- At least 15 people were killed Tuesday in a suicide blast in the northeastern Nigerian city of Maiduguri, the capital of Borno state, which has been bedeviled by the deadly Boko Haram insurgency, a witness and a paramedic said.
The explosion occurred when a homemade bomb, concealed in a van loaded with charcoal, went off at an ever-busy traffic circle outside the city's main market, according to a Twitter account by the Nigerian Defense Ministry.
Witnesses said the blast happened at about 8:00 a.m., when traffic was beginning to build at the roundabout, causing a major fire that engulfed vehicles and shops lining the streets.
Local vigilantes called Civilian JTF, after the special military unit battling Boko Haram, evacuated the victims of the morning blast to the State Specialist Hospital in the city.
"We have so far taken 15 dead bodies to the hospital from the blast scene, most of them women and boys," said a local vigilante Adam Kolo.
A journalist who was at the hospital confirmed seeing 15 bodies brought in by the rescue team.
A "rescue operation is still ongoing, which means the toll may change. We have also evacuated several people with injuries from the explosion," Kolo said.
"I saw several people lying lifeless on the street with six cars and three motorized rickshaws burning," said resident Ibrahim Mustapha.
Most of the victims were elderly women selling peanuts and kola nuts by the roadside and poor boys, Kolo said.
It is a custom in Maiduguri for residents to buy peanuts every morning and give them out as alms to poor boys begging on the streets.
The women vendors come out early in the morning and line the streets with their wares, waiting for residents leaving for work, while the child beggars mill around waiting for a generous buyer, Mustapha said.
Restive mobs besieged the area around the blast scene, barring reporters from taking photos of the carnage, and manhandled a photographer who wanted to take shots.
The mobs attacked and slightly injured four firefighters trying to quench the inferno at the scene, accusing them of not deploying fast enough to battle the fire.
"The youth were quite agitated and prevented us from taking photos of the scene and even descended on the firemen working to douse the fire," one of the reporters at the scene said.
Maiduguri has witnessed relative calm since last year, when local vigilantes sprang up and chased out Boko Haram insurgents into the bush, ending near-daily deadly bombing and shooting attacks.
The city has however witnessed isolated bombings and deadly attacks blamed on Boko Haram.