The incident occurred around 11:30pm on Wednesday
One other person was injured in the accident which took place on the Magurmari intersection of the Panchagarh-Tetulia highway around 1:30 pm on Friday, said the district's Superintendent of Police Md Yusus Ali.
The injured has been admitted to Panchagarh Sagar Hospital but the authorities could not immediately identify the victims.
"A passenger bus slammed into an auto-rickshaw travelling in the opposite direction. Four people died on the spot. The others were rescued and rushed to the district sadar hospital where they passed away."
Three of the dead passengers were women, according to the police officer.