Both the buses overturned and 28 people died on the spot and 10 were injured.
Many of the victims were going with families from Kholkholi in Dhubri district in the two mini buses to work in two brick kilns at Rangia in Kamrup district, police said.
The injured were admitted to Barpeta Medical College Hospital and Bongaigaon Civil Hospital.
Barpeta district administration has contacted its counterpart in Dhubri to inform the families of the deceased, they said.
The driver of the truck was absconding, they added.