According to The Associated Press, Chicago rapper Chief Keef has been taken into custody after a juvenile court judge decided a video of him firing a semiautomatic rifle at a New York gun range was a violation of probation. Keef, whose real name is Keith Cozart, was sentenced to 18 months' probation last year after being convicted of aggravated unlawful use of a weapon charges for pointing a gun at police officers. The 17-year-old MC is scheduled for a sentencing hearing on Thursday (1/17). Chief Keef's debut album, Finally Rich, was released in December.