A driver that was travelling along the A12 had the windscreen smashed after an object was dropped onto it.
Officers were called to the A12 at Marks Tey at about 5.50pm on Monday May 8.
A driver reported to police that an object was thrown at his car causing his window to smash.
A spokesman for Essex Police said no arrests have been made.
Anyone with information is asked to call 101 and quote crime reference 42/86960/23.
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