A lorry's windscreen has been smashed after large stones were allegedly thrown at a vehicle on the A14 on the outskirts on Ipswich.
Suffolk police said the incident happened on the eastbound carriageway at Sproughton shortly before midday on Wednesday.
A group of men were allegedly seen throwing unknown objects, believed to be large stones, onto a lorry as it passed under a bridge.
The lorry was left with a smashed windscreen and two objects hit the vehicle's body work.
One man was wearing a light blue hoodie with white or grey on the hood, while another was wearing a dark hoodie.
Two of the other men had brown hair, while a possible fifth suspect could not be clearly seen.
The men could not be found when officers arrived at the scene.
Officers are reminding members of the public that throwing objects at vehicles is a criminal offence.
Anyone with any information about this incident or who saw anything suspicious is urged to contact Suffolk police, quoting crime reference number 37/42571/21.
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