The major route has been closed following an earlier accident.
The A27 is closed westbound from the A259 Cathedral Way (Fishbourne Roundabout) to A259 Havant Road (Emsworth Junction), according to travel reports.
Traffic is moving slowly but queues are forming in most roads around the area. Eyewitnesses have reported seeing an air ambulance at the scene.
A car user Tweeted "Sat on the A27 towards Portsmouth awaiting the air ambulance to take off".
Chichester #a27closed due to a serious rtc
— Sussex News - Breaking news for Sussex (@SussexIncidents) June 12, 2021
Emergency services are on scene
Photes used with permission of R Van@SussexTW @brightonsnapper pic.twitter.com/dkQ5Pp1f4w
Update