We’re talking about the restrained guy who had been trying to help a woman and not once during the whole encounter had a gun in or near his hands? No, I would not murder that man, and I hope others wouldn’t either.
Yes you would respond to sudden gunshots with gunfire.
Yes agreed. Someone yells “gun gun” and they reacted thinking they were being shot at by the armed man that started an altercation with them.
But they heard "gun" and assumed it was the man who had been disarmed in plain view, and was being held down to the ground by 6 other agents. That's pathetic and disturbing. If he is that scared, he has no business holding a gun, let alone a job as a federal agent.