The dramatic development came a day after they "impeached" Speaker Nabam Rebia in a make-shift "assembly" premises in a community hall.
Khandu reiterated that Arunachal Pradesh is an integral part of India and people of the state would never give up their territorial rights.
The militants probably tergetted a few army vehicles parked there but the grenade hit an auto rickshaw coming from the opposite direction.
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.
'The pace of disbursement and project recommendation picks up as the tenure of the House draws near and usually all amount is released.'