Sunday morning’s crash in Daulatdia’s Canalghat at around 11am left another 34 people injured, Goalanda Ghat Police Station OC AKM Nasirullah said.
A Jhenaidah-bound bus and a Daulatdia-bound bus rammed into each other, killing three on the spot, he said quoting witnesses and victims.
A fourth victim died while being taken to hospital, he added.
Bus drivers Abu Shama and Jakir Hossain, and passengers Abdur Rahim and Ajgor Ali died in the accident.
Twelve of the injured have been admitted to Faridpur Medical College Hospital and 13 others are being treated at Goalanda Upazila Health Complex.
At least nine others were given first aid at the health complex, the police officer added.
Locals assisted police, fire service and local administration in the rescue.