Emergency services are on scene, including a fire crew from East Wittering, West Sussex Fire and Rescue Service has confirmed.
A spokeperson for the fire service said the incident involving a car and a tractor was ‘very serious’ but could not confirm injuries at this time.
Travel reports place the incident on the Birdham Straight between Church Lane and Crooked Lane.
Stagecoach tweeted to say a school bus was being held at the Academy Selsey with bus services unable to continue along the stretch until further notice.
Mortorists are being asked to follow an alternative route.
More to follow.