A gas leak, detected yesterday evening (February 1) has closed part of the Chichester by-pass, the A27.
Starting in the early evening, the road was reported as closed in both directions between the Bognor Road roundabout and the Oving crossroads.
It was still shut at 5.30am today (February 2).
According to West Sussex Fire and Rescue Service, firefighters have been attending as part of a multi-agency response.
Firefighters had this advice for anyone living nearby:
"Please stay inside and keep doors and windows closed.
"In general, people should avoid the area."
Emergency services also reported that gas engineers had arrived at the scene, and were working to fix the issue.