Hundreds of people had gathered for the annual spring carnival in Villepinte on Saturday and were getting ready to watch its climactic event – the lighting of the bonfire.
But the sudden explosion caused huge panic and some onlookers were hit by chunks of burning debris as they tried to escape the scene.
Fire officials said the gasoline used to light the fire was apparently mishandled, prompting the blast.
Five of those injured were taken to hospital with serious injuries, but officials said their lives were not in danger.
Officials said the explosion was found to be accidental, adding there were no signs of arson or terrorism.