Officers were called to the scene on Tinker Street at around 8.50pm on Tuesday night after reports that two vehicles had been involved in a head on collision.
A man in his 20s from Harwich, who had been driving a Ford Fiesta, was pronounced dead at the scene.
His next of kin has been informed.
After the collision, the A120 was closed in both directions by the Highways Agency between the B1035 at Horsely Cross and the B1352 at Ramsey.
A man driving a Vauxhall Corsa, which was involved in the collision with the Fiesta, was taken to hospital with serious injuries that are not believed to be life threatening.
A Toyota Rav 4 also collided with debris as it went through the collision scene.
No further injuries were reported.
Officers remain on the scene conducting recovery work.
Essex Police are calling for anyone who has any information about the incident to come forward. They are also looking to speak to anyone with dashcam footage of the Ford or Vauxhall prior to the collision.
Those with information should call the Serious Collision Investigation Unit on 01245 240590 or email collisionappeal@essex.pnn.police.uk.
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