One person has died and three people have received serious injuries after a road crash.
Emergency services were called to a collision between two cars on Essex Yeomanry Way, in Great Baddow, shortly after 1pm.
Both northbound and southbound carriageways of the A1114 near the scene are likely to remain closed until at least 5pm while police investigations continue.
An Essex Police spokesman said: "Long traffic delays are expected on roads around Chelmsford and drivers are urged to avoid the area.
"Any witnesses who have not yet contacted police, or anyone with information about events leading to the incident should contact the Essex Police Serious Collision Investigation Unit on 101 or email firstname.lastname@example.org"