The accident occurred around 9am on the Noakhali-Feni Highway in Senbag Upazila, said local police station chief Harun Or Rashid Chowdhury.
Police have not yet identified the victims.
The wounded have been taken to medical facilities in Senbag and Dagonbhuiyan, police said.
“A Ruposhi Bangla Transport bus travelling from Senbag to Chittagong collided head-on with another coming from the opposite direction. One person was killed on the spot,” said OC Chowdhury.
Two others died while undergoing treatment.