The accident took place on the Madhupur-Jamalpur Road, near Rupali Filling Station at 7 am on Friday, according to Md Tarique Kamal, chief of Madhupur Police Station.
The victims were a woman and her daughter from Dewangonj Upazila in Jamalpur and a man from Sreebordi Upazila in Sherpur, police said.
Police have not discovered the names of the victims.
The Madhupur-bound pickup van crashed head-on with the Jamalpur-bound CNG, killing the three victims on the spot, Md Tarique said.
He added that the vehicles were taken to the police station after the accident.