Nothing good will happen should they try to take the guns of the Americans. We are like the Spartans, many of us a warrior people ready to fight for our freedom and rights!
It would turn into civil war. Some would willingly give up their guns but many would not. And resorting to fighting for them would ensue and the police would have to start using deadly force, just as the citizens would.
It's a shame it would have to come to that but that is how it would be.