Earlier police had put the death figure at five.
Superintendent of Police Amit P Javalgi said the small vehicle turned turtle as it was overcrowded with 21 people.
The van was on its way to a picnic spot near 'Ramti Jhora' adjacent to Shyam Singh tea garden in Jalpaiguri district when it met with the accident in which four persons died on the spot and 16 others were injured, Javalgi said.
Six critically injured were referred to the North Bengal Medical College in Siligri, while ten others were admitted to the Mal Sub-Division hospital, he said.
