The blast went off outside a building frequented by a clan of the Camorra crime syndicate, Italy's Ansa news agency said.
Most of the victims werepassers-by. One of the injured was reported to be in a grave condition.
The blast and the resulting fire destroyed at least five other cars. It blew out windows in surrounding homes and blackened building facades up to their fifth floors.
The bomb was apparently on or under a stolen car parked outside the clan's meeting place. Authorities believe it may have been detonated by remote control.
The blast occurred in an area where two clans of the Camorra crime syndicate are fighting for control. Attacks that injure such a large number of bystanders are unusual even in gang wars; the authorities feared it might signal a worsening of hostilities.Reuse content