Terror warning shuts down German rock festival on opening night

German authorities have shut down a popular rock music festival because of a possible terrorist threat.The dpa news agency reported Friday that the Rock am Ring festival was cleared out on its opening night after Koblenz police said they'd received information of a "concrete threat."Organizers posted on the festival website that "due to a terrorist threat the police have advised us to interrupt the festival."It wasn't immediately clear how many fans were in attendance, but some 90,000 were expec