Bangladesh Premier Sheikh Hasina was accorded a warm welcome upon her arrival at the Government House, the Thai premier's office
The accident occurred around 3:15 pm on the Magura-Jashore Road in the Ramkantapur area on Sunday.
Two of the dead were men and two were women, but police have yet to confirm their names and identities.
The passenger bus, headed from Jashore to Magura, veered off the road and fell into the water of the ditch, said Masudur Rahman of the Magura Fire Service Station.
“The fire service received news of the incident, went to the scene and recovered four bodies from inside and beneath the bus.”
The bus was then lifted out using a crane, the fire service official said.
Mahbubur Rahman, the chief at the Shalikha Police Station, said a case was being prepared over the accident.