Thor wasted no time flying at the helicopter and saw no pilot. It was strange but it didn't matter He threw Mjolnir at it and the unmanned craft exploded in a fireball as the hammer smashed straight through the front, electrocuting the entire craft as it punched its way out the back of the helicopter and returned to Thor's hand.
"Twas not manned. The craft had no operator within it." It was a drone, operated remotely by someone. Thor watched the air ready to handle any other vessels like it. He would not allow another potential risk to this mission from an aircraft.
The son of Odin spun his hammer and ensured that no more outside interruptions would occur. He called upon the fury of the storm to create a hurricane around the city limits with the town itself safely situated in the eye of the oddly stationary and unmoving storm.
"None shall harm thee Bruce Banner. The Odinson shall ensure that none can reach thee. The Avengers seek the impressive intellect thou art reputed to possess. Thou would be a most valuable ally due to thy knowledge. We seek not to exploit thee, but to request thy aid and to join us to safeguard the future of the world from those who would see it all destroyed. I ask thee friend. Will thou consider becoming an Avenger?"