Swedish police say no arrests were made – and they have no suspects

Police in Sweden raided Justin Bieber‘s tour bus Wednesday night and say they have found a small amount of drugs on board.

One of the officers working the crowd outside the Globe Arena in Stockholm smelled a suspicious odor coming from the bus, prompting the raid, according to the Associated Press.

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Police spokesman Lars Bystrom told the AP that in addition to the substance – which local Swedish paper Aftonbladet reports is marijuana – a stun gun was found when officers boarded the empty bus parked under the concert venue in Stockholm, where Bieber was performing Wednesday. Bystrom also said that the substance had been sent to a laboratory for an analysis.

The pop star, 19, had entered the arena about a half-hour before the raid, according to reports.

The spokesman said several people were on the bus at the time of the raid, but police did not have a specific suspect, and no criminal charges were pending. A source confirms to PEOPLE that “no one was cited or arrested.” And a second source tells PEOPLE: “There were no violations.”

Bieber, who has been beset by various problems on his current tour, arrived Thursday in Finland, and wrote cryptically on Twitter: “some of the rumors about me….where do people even get this stuff. whatever…back to the music.”