Not really. Even an unorganized small group of armed people can create enough damage to the Police/Government forces that it's not worth the fight.
The sheer numbers and equipment of modern police and military forces are overwhelming. You need a lot of people, good organization, support from the inside.
Not to mention you'll be hit with the media first, discrediting all of your efforts and painting you as a terrorist or traitor in everyone's minds. Then you're easy pickings.