Five Trinamool Youth Congress workers were killed while four others injured when their SUV collided head on with a truck at Balapara area of Jalpaiguri district, police said.
The nine persons from Haldibari had come to Coochbehar to take part in a political programme and were returning when the accident occurred.
While four were declared dead on arrival at the hospital, one of the injured succumbed there, district Chief Medical Officer of Health, Prakash Medha, said.
The condition of the four remaining injured was stated to be serious.
The truck driver managed to flee after the accident, police said.