U.S. border agents stopped a bus touring with Canadian pop star Justin Bieber Sunday night, while entering Detroit on the Ambassador Bridge.

Chief Customs and Border Protection officer Ken Hamond told CTV News a search of the tour bus revealed an unspecified amount of marijuana and drug paraphernalia.

However Bieber was not on board.

The driver of the bus was issued a citation and was released.

The bus was headed to a concert at Joe Louis Arena.