Police have said a driver and passenger could have been seriously hurt after a brick was thrown from a bridge, smashing the windscreen of a lorry.
The brick, thrown from a bridge on the A64 in Tadcaster, hit a passing Leyland HGV at about 0710 BST on Wednesday.
The windscreen was shattered but the driver and passenger escaped unharmed.
Sgt Neil Dunn said: "This was a dangerous incident which could have been much more serious for the driver and his passenger."
Mr Dunn, of Selby Rural Safer Neighbourhood Team, said: "Fortunately they were uninjured but incidents like this can potentially lead to serious or fatal injuries.
"Whoever is responsible for this mindless act needs to realise what the consequences could have been. "
Witnesses or anyone with information are being asked to contact North Yorkshire Police.