He could have OJed them just as easily.
If he did not have a gun, he would of had a much more difficult time killing 2 people and severely injuring a third. Don't pretend a knife is as efficient of a killer. People don't hunt with knives for a reason. If we can force them into using something other than a gun, they would not be able to harm people so efficiently.
Guns don't necessarily need to be outlawed, but the ignorance in refusing to acknowledge their role in the amount of violence we see is baffling. There is a direct correlation between mass killings and guns being the method of choice. We should at least be able to have a serious conversation of what we can do to better ensure guns are secured, restricted from those who are dangerous, and as safe as possible.