Rihanna’s tour buses were stopped at the Ambassador Bridge on Wednesday morning and border officials say drug-sniffing dogs found a small amount of marijuana.

Kris Grogan, public information officer for U.S. Customs and Border Protection, says an entourage of 10 buses claiming association with the singer Rihanna were stopped at 9 a.m. while attempting to cross into Detroit at the bridge.

“During primary inspection, a U.S Customs and Border Protection officer referred the buses to secondary inspection due to the strong odor of marijuana which was emanating from one of the buses,” says Grogan.

One of the CBP canines alerted to the presence of drugs on one of the passengers during the secondary inspection, says Grogan.

“A search of that individual resulted in the discovery of a small amount of marijuana and a civil penalty was assessed and this individual was released,” says Grogan.

Rihanna was not on any of the buses.

The American singer had a concert in Toronto on Tuesday and is scheduled to play at Joe Louis Arena on Thursday.