In response to:
On top of all that, crowds disperse for cover when someone starts shooting. Mass shooters seldom go to ground or seek cover because they need to move around to pursue victims. They also obviously don't want anyone within arms-reach of them because they will be tackled and disarmed. So, no, they generally aren't in positions to create cross-fire problems if cops, security, or armed citizens attempt to bring them down after they start shooting. Never mind the fact that most self-defense weapons and ammunition are chosen for stopping power, where a bullet lodged into the target and transfers all it's momentum into the assailant rather than rips right through them.
It looks like all Ms. Marsden learned about guns she learned from Hollywood.
After a tragedy like the Sandy Hook Elementary School massacre in Newtown, Conn., the injection of anything short of seriousness into the subsequent public discourse about guns is touchy. But last week, the National Rifle Association blasted numerous rounds into that particular barrier with NRA Executive Vice President Wayne LaPierre's mouth.
The organization's hysteric solution to gun violence in America is to put designated sitting ducks -- er, "armed police officers" -- in every American school. Apparently the secret is now out that such places are "gun-free," and LaPierre says that "(gun-free school zones) tell every insane killer in America...
Again, without even considering whether the whole idea is good or bad, issues like crossfire and bystander safety have to be examined, not wished away.