Why does it take a horrible act of carnage for our country to come together?

The Virginia Tech macre reminds me of 9/11. It wasn' another country terrorizing us; however, it was, after all, carnage. Why would anyone need the type of gun he used? Something is wrong here. I have cried and prayed for the victims of Va Tech and the survivors, families and students. Everyone I have been in contact with can talk of nothing else and our country mourns AGAIN.