A commuter bus in traffic is believed to have been shot at on Värmdö, east of Stockholm.
The bus driver alerted the police shortly after 9 am on Thursday morning. At the terminal in Bullandö, a total of four of the bus's windows suddenly shattered.
Several people are said to have been on the bus at the time, but no one is reported to have been injured.
We don't know what happened, other than that the windows are broken. It could be that someone has shot at the bus with an airgun, it could be something else. We're talking to passengers and the bus driver and investigating the crime scene, says Daniel Wikdahl, the police's press spokesperson.
The police have launched a preliminary investigation into a weapons offence.