Why did authorities stopped Quavo's concert at Georgia Southern University on 18th April, 2015?

At Georgia’s Southern University, they had a Spring Bling concert. Both Quavo and Offset were arrested for marijuana possession, possession of a schedule II narcotic, as well as possession of a firearm. The stage manager had told the DJ to cut off the music because cops showed up.

All three members left the stage and were questioned by the police. They were also charged with carrying a gun on school property. The cops found cocaine, oxycontin, and codeine. Offset had been released from prison in October 2013. He is charged with gun possession by a convicted felon.