The Bieber tour bus was crossing the U.S. / Canadian border when a drug sniffing dog "alerted" border patrol agents to the possible presence of drugs on the bus and agents then conducted the search, finding the marijuana and paraphernalia, according to a statement Chief Customs and Border Protection Officer Ken Hammond made to E! News.

Hammond told the publication, "On July 28, a commercial touring bus attempted to enter the U.S. through Detroit via the Ambassador Bridge."

"The tour bus, associated with... Justin Bieber, was en route to a concert scheduled later Sunday night in Detroit. During the secondary inspection, a K-9 alerted to the presence of drugs and a subsequent search of the bus revealed marijuana and drug paraphernalia. Justin Bieber was not on the bus.