Perspective:
It's important to remember that yes these shootings are horrible and horrific and awful for all the people involved, but people in Iraq and Afghanistan and the Palestinian people in Israel get shot and killed like this every day. It's just as horrible and horrific and awful that their lives are cut down by our troops and Blackwater and the Israeli army. A life is a life is a life, no matter if it's an Iraqi or an Afghan or an American college student who gets gunned down. Murder is murder no matter where it happens and for whatever reason. That whole "Thou sahll not kill" extends to everyone, no matter if they are Christian or Muslim or atheist.

Causes:
It looks like the kid who did the shooting had mental problems and he did this when he went off his meds. I have no idea what kind of insurance the kid's family had or what those meds cost him but I'd be willing to be they were expensive and the high cost of those meds played a part in why he stopped taking them.
It's a shame that we don't put a person's mental health on the same plane that we put their physical health because as this case shows, and others like it have shown, it's more important in some cases to make sure the person is mentally healthy rather than physically healthy. We have always placed a stigma on mental problems in this country and we usually ostracize people who seek out help and we do the same when we find out someone has had mental health help in the past, I know for a fact that this is true because I saw how differently people treated my late father and my late sister when they found out they both had been treated for severe mental illness.
Instead of putting more money into helping the mentally ill for the past thirty years our government has done the cowardly thing and cut the funding because who's going to raise a hue and cry about the nut jobs losing a few million dollars in help? They've stolen that money that could have helped that poor kid and they've given it to big business so that they can sell us useless widgets and trinkets.
So while the shooter has to take some blame for what happened, we also need to blame our state and federal governments for cutting the funding for programs that could have saved the shooter and all his victims.
Help:
You know and I know the police in that area did the best job they could have done when they responded to this situation. I admire the police at times like these because they put their lives on the line to help stop more death and destruction.
Now I'm sure some asshat from the National Review or FOX Noise will scream, "Why didn't those college boys stop that kid? Why, hell if I had been there I'd have taken that gun away from that kid and I would have snapped his neck for doing that shit." And of course when they say shit like that it's obvious that they've never been shot at and they have no clue what they're talking about.
The impulse to save one's own life over saving others at a time like that is overwhelming. It's not sad or wrong or bad that you would hide under a desk or jump behind a door and let a shooter shoot and kill others, it's human nature. If a person pulled a gun on you and you had the chance to duck as they shot, you'd do it.
I've been shot at twice in my life. The first time was when I was 14 Cousin Psycho was about 400 yards away from me, I was standing outside the trailer we lived in at the time and he was across a field and on the other side of a creek, when he shot a .22 rifle at me. The bullet hit the side of the trailer and it just missed me by about a foot. I was so shocked that he shot at me that I ducked as soon as it hit. (To show you what a dysfunctional family I was in at the time I was the one who got into trouble in this incident because Aunt Rageaholic and Uncle Adultery, Cousin Psycho's mother and father, praised their son for admitting he shot at me and they got mad at me for being a tattletale when I told them it was their son who shot at me and hit their trailer.)
The second time was when I was in my early twenties and I was still in college. I was out in a seedy nightclub with a friend from college and my Cousin Skank, she is Cousin Psycho's sister. We were all well lit and we were having a grand ol' time. Then out of the blue some guy pulled a pistol from his coat and hit shot the wall near where I was standing. For a split second I thought it was a cap gun but when I saw the hole in the wall I yelled at my friend and my cousin to come with me and I ran out of there as fast as I could. I did not help them follow me, nor did I wrestle the gun from the shooters hand, my self preservation instinct took over and I ran the fuck out. And you'd do the same thing if you were ever shot at.

Solutions:
We're not going to magically become a less violent society because we get sick of these school shootings so what can we do to stop them?
Well, as far as I can tell if we enacted and enforced gun laws like they have in the UK, Canada, Japan, Germany, France, and Italy then we'd have far less incidents like this one at NIU. It's seems pretty cut and dried to me.
We need to close the loophole that lets people buy guns at gun shows with out having o go through a background check. We need to raise taxes on guns and ammo so that they stay out of the hands of people who are unstable or dumb enough to do something like this for whatever twisted glory they may get. And finally we need to stop kowtowing to the NRA and we need to stop letting them write gun legislation.
I think of this song every time there is a shooting. My heart goes out to all the parents and to all the people who've been killed by guns the world over.