Police said the mangled bodies of the four were extricated from the twisted car while three others were rushed to hospital and their condition is stated to be serious.
The seven were coming to Kolkata in the early hours. The driver could not spot a truck, parked on the side of the highway, due to fog and rammed into it from behind.
The deceased were identified as Sachi Chowdhury (29), Bhim Mondal (38), Sankari Ghosh (38) and Amitabha Guho, police said.
The seven were residents of Belur and Liluah areas of neighbouring Howrah district.