The Virginia Tech Murders were the worst ever in modern Time. Why is it that history is ignored?

I feel really sad for the VT victims, but I also feel bad that media ignored history. 300 Natives in the 1860's were Macred at Bear Creek, Utah, 300 died at Wounded Knee, South Dakota in 1890. There are many other instances where Native people were killed by insane people. Why does the media not look into the history of America before it makes Blanket statements?