The incident took place late last night on Gwaldam-Karnaprayag road when the vehicle fell into a 500 ft deep gorge, killing all its occupants including the driver on the spot, they said.
The deceased have been identified as Chapal Kantidhar Chaudhry (62), his wife Lipika Chaudhry (54) and their son Kushal Chaudhry (22). The driver of the vehicle is yet to be identified, they said.
The kin of the deceased tourists from West Bengal have been informed and further investigations are on, they said.