An Army helicopter crashed at Migging in Upper Siang district of Arunachal Pradesh on Friday morning, a defence official said.
The advanced light helicopter, carrying Army personnel, was on regular sorties, he said.
The incident took place at 10.43 am, and search operation is underway, the official said.
Upper Siang SP Jummar Basar said the crash site is a mountainous region, and it would take time for the search and rescue team to reach the spot.
This is the second incident of an Army helicopter accident in the state this month.
A Cheetah helicopter crashed in Tawang district on October 5, killing one of the two pilots onboard.
Another Cheetah chopper crashed in March near the Line of Control in Jammu and Kashmir. The pilot died in this incident, too.