Indeed @Enron, copy cat is the ideal word. Its the whole culture around violence and how you glorify it as a society.
Its big fantasy type of way for losers and crazies to go out, big scenario media helped build up, so you will keep seeing this happen, even with better gun control. Even if it would help to be stricter instead basically shop guns while you buy your burritos type of fare as it is in big parts of the country. Easier to jump to that option for crazies when they dont have to go through any hoops or checks I guess. Can defenitely limit this and make it harder. But this is for the crazies part, actual criminals will find their guns regardless on strictness or not.