They have a person with a gun to blame. And hundreds of millions?? You exaggerate greatly. There are only 329 million people in the U.S., which is where the bulk of gun owners are in the world, and where we are talking about. Less than 40% of them own guns, putting that figure at around 125 million. 125 million, is not "millions".
But of the 125 million who are rational, sensible, and responsible gun owners, how many agree we should do nothing about the gun problem we see in this country? If they are all as insane as that, then I would be even more concerned than I am about this country, where school shootings are just the price to be paid for our freedoms, for f*s sake.
And, if guns don't kill people, then would you support sending a soldier to the front line without a gun? Why would they need a gun, if it's just people who kill people?