I'm pretty sure everyone on here agrees with the idea that a determined attacker will use whatever is available, with or without guns, to wreak havoc if he's determined enough. I'm just surprised it took this long; I figure it would be easier for someone to swerve their SUV onto the sidewalk and take out the line waiting to get into a nightclub or plow into any kind of gathering than it would be to acquire guns and sneak them into a building. Can you imagine someone going berserk on the people waiting in line for Black Friday?
Well, hopefully this story helps if you're discussing the pros and cons of firearm ownership with someone.