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".
Following a single vehicle collision on the #a27 between #Chichester and #Emsworth the road is now fully opened. Thank you for your patience but it was essential to get the best care for the 3 Yr old passenger. Amazing work from @SECAmbulance and @airambulancekss as usual 👌 pic.twitter.com/v9Hrtw0QKL— PC Pete May (@sussexroadscop) June 12, 2021