Norfolk police is appealing for information after reports of bricks and glass being thrown from a bridge over the A11 in Attleborough.
At about 2.30pm on Wednesday, bricks were thrown from the Besthorpe Road Bridge, damaging the windscreen and roof of one vehicle and the front bumper of another.
And at 1.20pm today (Friday), reports were also received of a unknown man throwing glass from the same bridge, although it is believed there was no damage caused to any vehicles.
This man is described as wearing a pink jacket and a hat with flaps which covered his ears.
He was also seen riding a bike.
Anyone who may have witnessed the incident, or has any information regarding it, should contact PC Steven Howard at Attleborough Police Station on 101.
Alternatively contact Crimestoppers anonymously on 0800 555111.