Fifteen men and a child were among those killed in the accident which took place about 7:30 AM, police said.
While 12 people died on the spot, three others died after being taken to Malda Medical College and Hospital, officials said.
The victims were returning to their homes at Raiganj in neighbouring north Dinajpur district after attending a wedding reception at Sahapur near Malda town.
The highway has been closed after the accident. The police and fire brigade personnel have rushed to the spot.