>> welcome back to dateline. the walton boys had made it out of the west gate mall which was still a scene of terror. but their mother, katherine, and her three girls, were still trapped inside, and then, a man holding a gun approached them. the next moments would be critical. here is kate snow with the conclusion of our story. >> for more than four hours, katherine walton, her girls, and the kenyan woman helping them, huddled in a hiding space barely bigger than a bathtub closed off from the outside world. katherine didn't know she was part of a terrorist attack. all she knew was that gunman were convincing the mall, shooting it everyone. and now, a man with a gun was creeping toward her. >> you run to that table for hours. at some point, you hear something, you see something?