Fifteen people were killed and many others injured when a truck carrying them fell into a gorge at Kheel, 70 km from Itanagar, police said on Friday.
The Superintendent of Police, Robin Hibu, said, quoting a report that the accident occurred in a deep forest area on Thursday evening.
The rescue teams, which were sent from different places like Sagalee and Doimukh, were yet to reach the accident-prone remote area, he said.
There were in all 20 people in the truck, which was returning from Sagalee to Doimukh, he added.
Meanwhile, state's Chief Minister, Gegong Apang, has announced an ex-gratia payment of Rs 50,000 to the next of kin of each deceased and said that the government would also bear expenses for the treatment of the injured.
Apang has also ordered an inquiry into the reasons for frequent accidents in the area.