Police said the water chute, one of the most popular rides of the park collapsed due to overcrowding.
There were more visitors to the park in view of the festival season.
Following the collapse, relatives and friends of those injured went berserk and went on rampage. Police rushed to the spot and not much damage was caused by them, the police said.
The injured were admitted to nearby Calcutta Heart Research Centre from where they were transferred to Apollo Hospital and AMRI Hospital.
DC (Hq) of Bidhannagar commissionerate Subrata Banerjee said the six seriously injured had fractured legs, arms or shoulders.
Police are investigating whether there was any negligence on the part of the park's authorities.
The park authorities could not be contacted over the incident.
