Five others were injured in the accident that took place near a roundabout on the eastern side of the Bangabandhu Bridge around 7:30 am on Friday, said Bangabandhu Bridge (East) Police Station OC Kazi Ayubur Rahman.
"A speeding black microbus heading towards Dhaka rammed into the back of a covered-van, operated by Ahmed Parcel Service, about 200 yards away from the toll plaza," he said.
"The microbus was wrecked in the collision while the rear end of the van was also damaged."
Police and fire service personnel subsequently rescued five people from the scene before sending the victims to Sirajganj Sadar Hospital.
The injured were Fatema's husband Haji Selim, 32, their two-and-a-half-year-old son 'Sami', Selim's sister 'Runa', 27, Meghla Haque and Imdadul Haque, 40.
Police are preparing legal action over the incident, said the OC.