All the victims were passengers of the SUV and members of a group which sang 'kirtan' - a form of devotional song.
Altogether 12 persons including the driver were in the SUV returning to Ganga Prasadpur in Chakdaha in the district from Duttapulia after a programme there when the accident occurred at about 1:45 am.
Two persons were killed on the spot and four others died at Ranaghat Sub-divisional Hospital later, sources said. The six injured were taken to Ranaghat Sub-divisional Hospital. Five of them were later referred to a Kolkata hospital in a critical condition.
The sources said it was raining when the accident took place. The police seized both the vehicles. The driver of the private bus fled.