The deceased were identified as Mohammad Golam Sarwar, 40, his four-year-old daughter Muskan, and Sagor, 25, of Nikli upazila in Kishoreganj.
The injured are Sarwar’s wife Umme Salma, 32, their son Ahmed Imtiaz, 9, and driver Gias Uddin, 30. All the victims were residents of Uttara’s Sector 10 in Dhaka.
Police and locals said the Chattogram-bound private car from Dhaka lost control and rammed into a stationary covered van from behind at Thakur Dighi area of Jorarganj around 8 am.
Sarwar and his daughter Muskan died on the spot, while Sagor succumbed to his injuries after being rushed to Chattogram Medical College Hospital (CMCH).
Relatives said Sagor worked at a furniture factory in Chattogram city and often traveled the Dhaka-Chattogram route for official purposes.
Jorarganj Highway Police Sub-Inspector Borhan Uddin said the bodies are in police custody.
Shafayat Hossain, station officer of Mirsarai Fire Service, said the private car (Dhaka Metro Gha-13-7348) was completely mangled in the crash, which is suspected to have occurred as the driver fell asleep at the wheel.