The collision took place between a Guwahati-bound night bus carrying at least 28 passengers and a truck which was going to Tinsukia at around 11 last night.
While two persons died on the spot, the injured 25 were taken to Jorhat Medical College and Hospital.
Six of them were later shifted to Assam Medical College and Hospital in Dibrugarh, police said.
Drivers of both the vehicles were among the injured.