A driver suffered cuts to his neck and arms when an item was dropped onto his windscreen from a bridge on the A13.
Essex Police received reports of a piece of "hardcore" being thrown from a bridge over the major road, which runs from Barking and Havering in east London to Essex.
The incident took place on July 21 at Fobbing at 6.05pm, with the item smashing the vehicle's windscreen and leaving the driver with cuts to his neck and arms.
Police would like anyone with information, CCTV, dash cam or other footage in relation to the incident to get in touch with the reference number 42/203277/22.
Essex Police can be contacted by its website or by using its online live chat at https://www.essex.police.uk/digital101.
Alternatively, call 101 or, in an emergency, 999.
To make an anonymous report, call Crimestoppers on 0800 555 111.
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