WASHINGTON -- A female Chinese graduate student has been decapitated by a fellow student at Virginia Tech, the scene of the worst school shooting in US history in 2007, police said Thursday. At approximately 7:00 p.m. Wednesday, Xin Yang, a 22-year-old graduate student from Beijing, was killed at an Au Bon Pain cafe on the Virginia Tech campus in Blacksburg, Virginia, university officials said. They added that emergency contact records suggest that Yang and the student who murdered her, Haiyang Zhu from Ningbo, China, knew each other. According to officials, witnesses said Zhu, 25, attacked Yang with a knife. "There were seven witnesses in the cafe. There had been no argument, no shouting" when the young woman was attacked, said Virginia Tech spokesman Mark Owczarski, confirming that Yang had been decapitated. "This is horrible and tragic. Especially when we know that Virginia Tech has got its share of hardship and horror." Yang had arrived at Virginia Tech in e...