I would never shoot an unarmed person; that would be murder. Gun possession is also not a reason for anyone to be shot. However, by all reports these agents are menacing people with their weapons, bundling people into unmarked vans, etc. Those behaviors threaten lives, and responsible gun owners will intervene to stop them.

If they are not wearing badges and identification of which agency they are operating under the authority of, then the laws should be that they are not legally operating as federal officers. That's the point. I'm allowed (in many jurisdictions) to defend myself with deadly force if necessary against an assailant. Without properly identifying themselves as federal agents, they could be any random person who bought camo and tactical gear at any random gun shop or military surplus store.

Federal agents should be required to clearly identify themselves as such.