The so-far unsung hero of the New Zealand massacre was not, per U.S. gun-sissy lore, a good guy with a gun. Abdul Aziz Wahabzadah, a refugee from Afghanistan, was with his four sons at the second mosque the gunman went to. He heard gunshots, looked out a window, and saw the killer, armed with an assault rifle, running toward the front door. So he ran out to meet him, armed only with a credit card processing machine.
He tells the rest of his story here.