A police officer said the cylinder, used by a hawker to inflate balloons, suddenly exploded injuring the people surrounding him at Karbala fair ground, held on the occasion of Muharram.
The six injured, including the hawker, were rushed to a local private hospital at the initiative of Uluberia MP Sultan Ahmed who visited the site.
Ahmed said the injured included two children.
The police officer said quoting hospital doctors one of the six injured was in serious condition.