At around 7.30am on Saturday April 15th officers attended a two-vehicle RTC in Maldon Road, Colchester.
A silver Vauxhall Corsa and maroon Mazda were involved in a collision at the junction of Maldon Road and Roundbush Road.
A 23-year-old man was taken to hospital in London with serious injuries and is in a critical but stable condition.
A woman was also taken to hospital with minor injuries.
Witnesses and anyone with dash cam footage or CCTV are asked to contact Pc Grant Fryatt on 101.