The ship carrying the Bangladeshis will bring back Myanmar security personnel who crossed the border recently amid fighting with rebels
Amtali Police Station OC Md Shahid Ullah said the three, deputed to Patuakhali Coastguard, were riding a motorcycle when the bus hit it face-on in Bandra on Friday afternoon.
Police have identified the victims as Fuad Hossain, 23, Abdus Sadeq, 30, and Enamul Haque, 30.
Sub-Inspector Abdul Khaleq said Fuad and Sadeq died on the spot while Enamul died in Kolaparha Hospital in Patuakhali.
The bus was seized but the driver had fled the scene, he added.