The four people on board included the pilot, crew and District Collector of Tirap district Kamlesh Joshi in the Dauphin N3 helicopter, which lost touch with the Air Traffic Control after taking off at around 11 am.
The helicopter was last located through signal at 11:30 am. The chopper was on its way from Dibrugarh to Khonsa and then to Lumding in Assam.
"We are trying to contact the pilot but as of now no link has been established with the missing helicopter," sources told PTI.
More details awaited.