The alleged incident took place yesterday when the chief minister was on his way back from Uttarkashi district where he had gone to distribute relief to residents of a fire-ravaged village.
When the chief minister's helicopter was about to land at the GTC helipad, the pilot spotted two drums allegedly placed by Army personnel on the 'H' (arena identified for landing) at the helipad, an official said.
The reason for their suspicion was that when Rawat's convoy was heading for the helipad at noon yesterday, its way was allegedly blocked by a private Honda City car of an Army officer.
As the convoy was about to reach the gate of the Golf Ground at the GTC helipad, the car in which the Army officer was sitting, pulled up at the gate blocking the convoy's way, an entry made by the Cantonment Police Station said.
However, when the officer was repeatedly told that his car was blocking the way, the car was driven away, the entry made at the police station said.