The incident occurred around 11:30pm on Wednesday
The accident occurred on the Dinajpur-Phulbari Highway in the Sadar Upazila's Chuniapara around 10am on Thursday, said Kotoli Police OC Redwanul Rahim.
"A bus headed to Dinajpur from Phulbari collided head-on with an autorickshaw travelling in the opposite direction. Three passengers in the autorickshaw died on the spot," said the OC.
The injured have been admitted to Dinajpur M Abdur Rahim Medical College Hospital, he added.