The accident took place at around 5 a.m. in the Balijan area near Dergaon.
Golaghat SP Rajen Singh said: “All the deceased and injured persons were travelling by the bus which was heading towards Tilinga Mandir from the Kambandha area of the district. It suffered a major collision with the truck which was coming from the opposite direction.”
According to the police, 10 people died on the spot and the remaining two succumbed to their injuries at the Jorhat Medical College and Hospital.
Further details are awaited.