Dorset Police is appealing for information following a dangerous incident on the Upton bypass in Poole.
At around 7.55pm on Monday April 20, a car was struck by a stone while travelling between the Upton and Creekmoor junctions.
The windscreen was damaged, but the driver, a man in his twenties, was not injured.
Two young people were seen on a bridge above the road at the time.
Police say the behaviour was extremely dangerous and could have caused serious harm.
Officers carried out searches in the area but have not yet identified those responsible.
Anyone who witnessed the incident or has dashcam footage is urged to contact police quoting the reference number.
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