A couple and their daughter were killed as a bus hit their motorbike on Thakurgaon-Baliadanga road in Sadar upazila of the district Sunday morning.
The deceased were identified as Masudur Rahman, 55, his wife Hasina Begum, 45 and their 14-year-old daughter Meger Negar Simi. They were residents of Mathurapur village in Sadar upazila.
Police and witnesses said riding on the motorbike the couple was taking their daughter to a madrasha as her annual examination was going on.
The Dhaka-bound bus of "Hanif Paribahan" rammed into the motorbike in Palli Vidyut Bilpara area around 10:30am, leaving Hasina dead on the spot and two others critically injured, they said.
Masudur and his daughter succumbed to their injuries after they were admitted to Sadar Hospital.
The doctor on duty at Thakurgaon Modern Sadar Hospital said that one person died on the spot. Two others died while undergoing treatment at the hospital.
Kamal Hossain, officer-in-charge of Sadar police station, said drive is on to arrest the bus driver.